Pressure-propelled system for body lumen

ABSTRACT

Apparatus ( 10 ) is provided for use with a biologically-compatible-fluid pressure source ( 16 ), the apparatus ( 10 ) including an elongate carrier ( 26 ), adapted to be inserted through a proximal opening ( 18 ) of a body lumen ( 20 ), and a piston head ( 30 ) coupled to a distal portion of the carrier ( 26 ). The piston head ( 30 ) is adapted to form a pressure seal with a wall of the lumen ( 20 ) after the carrier ( 26 ) has been inserted into the lumen ( 20 ), and to be advanced distally through the body lumen ( 20 ) in response to pressure from the fluid pressure source ( 16 ). The apparatus ( 10 ) is configured to facilitate distal advancement of the piston head ( 30 ) by facilitating passage of fluid out of the lumen ( 20 ) from a site within the lumen ( 20 ) distal to the piston head ( 30 ). The apparatus ( 10 ) additionally includes an optical system ( 32 ), coupled to the carrier ( 26 ) in a vicinity of the distal portion, the optical system ( 32 ) having distal and proximal ends. The optical system ( 32 ) includes an image sensor ( 232 ), positioned at the proximal end of the optical system ( 32 ); an optical member ( 234 ) having distal and proximal ends, and shaped so as to define a lateral surface, at least a distal portion of which is curved, configured to provide omnidirectional lateral viewing; and a convex mirror ( 240 ), coupled to the distal end of the optical member ( 234 ), wherein the optical member ( 234 ) and the mirror ( 240 ) have respective rotational shapes about a common rotation axis.

CROSS-REFERENCE TO PRIOR APPLICATION

This application was filed under 35 U.S.C. 371 as a national stage ofPCT/IL05/00008, filed Jan. 3, 2005, claiming the benefit under 35 U.S.C.119(a) of U.S. Provisional Application No. 60/571,438 filed May 14,2004, and U.S. Provisional Application No. 60/607,986, filed Sep. 8,2004, and is a continuation of U.S. patent application Ser. No.10/753,424 filed Jan. 9, 2004, now U.S. Pat. No. 7,833,176, and is acontinuation of U.S. patent application Ser. No. 10/838,648 filed May 3,2004, now U.S. Pat. No. 7,635,345, and is a continuation of U.S. patentapplication Ser. No. 10/967,922 filed Oct. 18, 2004, now U.S. Pat. No.7,635,346.

All of the above-mentioned applications are assigned to the assignee ofthe present application and are incorporated herein by reference.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation-in-part of, and claimspriority from:

(a) a U.S. patent application to Cabiri et al., filed Oct. 18, 2004,entitled, “Pressure-propelled system for body lumen,”

(b) U.S. patent application Ser. No. 10/838,648 to Gross et al., filedMay 3, 2004, entitled, “Pressure-propelled system for body lumen,” and

(c) U.S. patent application Ser. No. 10/753,424 to Gross et al., filedJan. 9, 2004, entitled, “Pressure-propelled system for body lumen.”

The present application claims priority from:

(a) U.S. Provisional Patent Application 60/607,986 to Cabiri et al.,filed Sep. 8, 2004, entitled, “Mechanical aspects of pressure-propelledsystem for body lumen,” and

(b) U.S. Provisional Patent Application 60/571,438 to Dotan et al.,filed May 14, 2004, entitled, “Omnidirectional and forward-lookingimaging device.”

All of the above-mentioned applications are assigned to the assignee ofthe present application and are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a pressure-propelled system,suitable for imaging body lumens, such as the gastrointestinal (GI)tract.

BACKGROUND OF THE INVENTION

Many imaging devices are known for producing medical images of bodylumens, such as the gastrointestinal (GI) tract. For example, endoscopyis widely used for observing, photographing tissue, and taking specimensfrom lesions and the like. In a conventional method of examining a colonusing an endoscope, for example, the endoscope is typically manuallyinserted into the colon. In this manual technique, patients may oftencomplain of abdominal pain and distention because the colon is extendedor excessively dilated, thereby necessitating stopping the endoscopicprocedure. Furthermore, it is not unusual for the colon to bleed and beaccidentally perforated. Insertion of an endoscope through the sigmoidcolon and into the descending colon, or through the splenic flexure, thetransverse colon, the hepatic flexure or parts affected by previousoperations may also be accompanied with difficulty. Because of thesereasons, a colonoscopy is typically performed by a relatively smallnumber of skilled practitioners, and the rate of patient pain anddiscomfort is high.

U.S. Pat. No. 5,337,732 to Grundfest et al., whose disclosure isincorporated herein by reference, describes a robot for performingendoscopic procedures, which includes a plurality of segments attachedto each other through an articulated joint. Actuators can move thesegments together and apart and change their angular orientation toallow the robot to move in an inchworm or snake-like fashion through acavity or lumen within a patient. Inflatable balloons around thesegments inflate to brace a temporarily stationary segment against thelumen walls while other segments move. A compressed gas line attached tothe back segment provides compressed gas to inflate the balloons andoptionally to drive the actuators. The lead segment includes atelevision camera and biopsy arm or other sensors and surgicalinstruments.

US Patent Application Publication 2003/0168068 to Poole and Young, whosedisclosure is incorporated herein by reference, describes a method forlining a body cavity with a liner that contains two chambers by (a)selectively controlling fluid pressure in a first of the chambers so ascause the first chamber to evert and advance into said body cavity, and(b) selectively controlling fluid pressure in a second of said chambersto control the stiffness of the liner.

US Patent Application Publication 2003/0105386 and U.S. Pat. No.6,485,409 to Voloshin et al., whose disclosures are incorporated hereinby reference, describe endoscopic apparatus comprising an inflatablesleeve, wherein inflating the sleeve causes an endoscope to be advancedinto the colon.

US Patent Application Publication 2002/0107478 to Wendlandt, whosedisclosure is incorporated herein by reference, describes aself-propelled catheter, wherein pressurizing an everting tube coupledto the catheter advances the catheter into the body.

U.S. Pat. No. 6,702,735 to Kelly, whose disclosure is incorporatedherein by reference, describes a device for moving a tool along apassage. The tool is coupled to an inflatable sheath, such that as thesheath is inflated it extends into the passage and carries the toolalong.

U.S. Pat. No. 5,259,364 to Bob, et al., whose disclosure is incorporatedherein by reference, describes an endoscopic device comprising aflexible eversion tube, wherein inflating the eversion tube causes anendoscope to be advanced into a body cavity.

U.S. Pat. No. 4,403,985 to Boretos, whose disclosure is incorporatedherein by reference, describes a catheter containing ports near itsdistal end through which high pressure fluid is forced to advance andsteer the catheter.

U.S. Pat. No. 4,176,662 to Frazer, whose disclosure is incorporatedherein by reference, describes an endoscope having a propulsionmechanism and at least one transmitter at the distal end transmittingbursts of energy waves for tracking the position of the distal end. Thepropulsion mechanism consists of two radially expandable bladdersseparated by an axially expandable bellows with only the forward bladderattached to the distal end so that by expanding and contracting them inproper sequence, propulsion of the endoscope is achieved.

U.S. Pat. No. 4,148,307 to Utsugi, whose disclosure is incorporatedherein by reference, describes a tubular medical instrument having atleast one cuff assembly including two cuffs disposed on thecircumference of a flexible sheath, spaced at prescribed intervals andmade expansible only in a radial direction of the flexible sheath, and adeformable propellant cuff having a doubled-back section, disposed alsoon the circumference of the sheath between the two cuffs. When air isintroduced into, or drawn from, the three cuffs selectively, theflexible sheath automatically advances step-by-step in a human bodycavity.

U.S. Pat. No. 5,906,591 to Dario et al., whose disclosure isincorporated herein by reference, describes an endoscopic robot, adaptedto be inserted into a body cavity of a patient and to be advancedtherein using “inchworm-like” motion.

U.S. Pat. No. 6,007,482 to Madni et al., whose disclosure isincorporated herein by reference, describes an endoscope having a pairof telescoping sections at its distal end, one of which carries acamera, and which are alternately actuated to provide movement through abody passageway by a Bowden type of cable. Respectively attached to thetwo cylindrical sections are inflatable bladders which provide for themovement.

U.S. Pat. No. 5,662,587 to Grundfest et al., whose disclosure isincorporated herein by reference, describes an endoscopic robot having aplurality of segments attached to each other. Traction segments embracethe walls of a body lumen. Other segments include actuators that causethe endoscope to locally deform its shape via bending, extending, orsome combination of bending and extension. A method is provided tosequence the action of the segments to cause “inchworm-like” or“snake-like” locomotion, or a combination of them through a curved andflexible lumen. A compressed gas line attached to the back segmentprovides compressed gas for insufflation of the lumen, and canoptionally be used to drive the actuators that control the operation ofthe endoscope segments.

U.S. Pat. No. 4,690,131 to Lyddy, Jr. et al., whose disclosure isincorporated herein by reference, describes a combination of elementsadapted to be used with an endoscope, and capable of at least partiallyextending with the instrument into the lumen of a tubular body part,such as the large intestine. A sheath is adapted to be mounted on theendoscope. The endoscope and sheath are provided with selectivelyinflatable cuffs movable with respect to one another by axially slidingthe sheath on the endoscope.

U.S. Pat. No. 4,040,413 to Ohshiro, which is incorporated herein byreference, describes an endoscope comprising a tube having one or moreinflatable balloons on an outer surface thereof. A fiber optic bundlepasses through the tube to a distal flexible portion of the tube, forviewing an interior of a body cavity. When only one balloon is provided,the balloon is provided on one side of the tube near the end thereof toenlarge the space within a body cavity in one direction so that there issufficient space in this direction for the flexible portion of the tubeto bend in this direction, and to thereby obtain a large field of view.When more than one balloon is provided, one of the balloons isselectively inflated to enlarge the space within the body cavity in thedesired direction. In an embodiment, an outer sleeve is provided aroundthe tube with balloons on the outer face thereof and is made slidablewith respect to the tube. The outer sleeve and the tube are insertedinto the body cavity by alternately inflating the balloons on the outersleeve and those on the tube to facilitate the insertion thereof intothe body cavity.

U.S. Pat. No. 6,503,192 to Ouchi, which is incorporated herein byreference, describes an insertion facilitating device for an intestinalendoscope. The device has a cylindrical body in which an insertionportion of the endoscope is inserted while holding an anal sphincter ofa patient in an open position. The cylindrical body is provided at oneend thereof with a conical opening. In an embodiment, the cylindricalbody is provided on its inner surface with a pressure leakage preventionring made of a sponge material, for preventing leakage of internal airof the patient's body.

US Patent Application Publication 2003/0083547 to Hamilton et al., whichis incorporated herein by reference, describes methods and apparatus forinhibiting longitudinal expansion of a body portion of an endoscopicsheath during inflation of an inflatable member. In one embodiment, asheath assembly includes a body portion adapted to encapsulate a distalend of an insertion tube, and an inflatable member coupled to the bodyportion and adapted to be inflated radially outwardly from the bodyportion. The sheath assembly further includes an expansion-inhibitingmechanism coupled to at least one of the inflatable member and the bodyportion. The expansion-inhibiting mechanism is described as inhibitinglongitudinal expansion of the body portion during inflation of theinflatable member. The expansion-inhibiting mechanism may comprise, forexample, a non-compliant member, a longitudinally-stretched portion, areinforcing spring member, a pressure relief device, or a suitabledetent mechanism.

PCT Publication WO 04/069057 to Gobel, which is incorporated herein byreference, describes a device for use in healing processes, comprising aflexible double-walled inflatable tube segment which encloses a hollowspace.

US Patent Application Publication 2003/0000526 to Gobel, which isincorporated herein by reference, describes techniques for controllingthe breathing gas flow of a ventilator for assisted or controlledventilation of a patient as a function of the tracheobronchial airwaypressure of the patient. The techniques include introducing a ventilatortube, such as a tracheal tube or tracheostomy tube, into the trachea Thetube is subjected to breathing gas, and is equipped with an inflatablecuff and at least one lumen that is continuous from the distal end ofthe tube to the proximal end of the tube. The tube is adapted to detectthe airway pressure by continuous or intermittent detection andevaluation of the intra-cuff pressure prevailing in the cuff of thetube. The breathing gas flow of the ventilator is controlled as afunction of the intra-cuff pressure detected.

PCT Publication WO 03/045487 to Gobel, which is incorporated herein byreference, describes a bladder catheter for transurethral introductioninto the urinary bladder by the urethrae, consisting of an elasticcatheter shank with a fillable balloon element secured thereto andconnected to a filing channel incorporated into the wall of the cathetershank. The balloon element and the catheter shank are made ofpolyurethane, a polyurethane-polyvinylchloride mixture, or similarpolyurethane-based material.

SUMMARY OF TIE INVENTION

Some embodiments of the present invention provide an imaging systemwhich is propelled by fluid pressure through a body lumen, such as thegastrointestinal (GI) tract. Embodiments of the invention are describedhereinbelow with reference to the GI tract, but it is understood thatthese embodiments are not limited to use in the GI tract, and may beused for other body lumens as well. Unlike the prior art, which mayinflate and anchor balloons and similar devices to the GI tract wall inan attempt to overcome the low friction of the GI tract, theseembodiments of the present invention utilize the very low frictionenvironment of the GI tract to propel the imaging system, typically withno need for anchoring.

There is thus provided, in accordance with an embodiment of the presentinvention, a system including a guide member at least partiallyinsertable into a proximal opening of a body lumen, the guide memberincluding a first passageway connectable to a source of fluid pressure,an elongate carrier arranged for sliding movement through the guidemember, and a piston head mounted on the carrier, wherein a greaterfluid pressure acting on a proximal side of the piston head than on adistal side of the piston head propels the piston head and the carrierin a distal direction in the body lumen.

The system of this embodiment of the invention may have differentfeatures. For example, the piston head may be inflatable. The carriermay include a second passageway in fluid communication with the pistonhead, which may be connected to a source of fluid pressure for inflatingthe piston head. A vent tube may pass through the piston head, having anopening distal to the piston head through which fluid may be vented tothe outside. An image-capturing device may be mounted on the carrier,such as distal to the piston head. A power supply tube may pass throughthe carrier and may be connected to the image-capturing device. A fluidsupply tube may pass through the carrier and may be connected to a fluidsource.

In accordance with an embodiment of the present invention, an auxiliarypiston head may be mounted on the carrier proximal to thefirst-mentioned piston head. The auxiliary piston head, which may beinflatable, may be fixed axially to the carrier at a fixed or variabledistance from the first-mentioned piston head. The carrier may include athird passageway in fluid communication with the auxiliary piston head,which may be connected to a source of fluid pressure for inflating theauxiliary piston head.

There is therefore provided, in accordance with an embodiment of thepresent invention, apparatus for use with abiologically-compatible-fluid pressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a distal piston head coupled to a distal portion of the carrier andadapted to:

-   -   be in direct contact with a wall of the lumen when the carrier        is inserted into the lumen,    -   be advanced distally through the body lumen in response to        pressure from the fluid pressure source, and    -   facilitate passage of fluid out of the lumen from a site within        the lumen distal to the piston head.

In an embodiment, an outer surface of the piston head in contact withthe wall of the lumen includes a low friction coating suitable forfacilitating sliding of the piston head against the wall of the lumen.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe piston head is adapted to be in direct contact with a wall of the GItract when the carrier is inserted into the GI tract. For example, theGI tract may include a colon, and the piston head may be adapted to bein direct contact with a wall of the colon when the carrier is insertedinto the colon.

In an embodiment, the apparatus includes a vent tube, and the pistonhead is adapted to facilitate the passage of the fluid out of the lumenthrough the vent tube. For some applications, the vent tube is shaped todefine an inner diameter thereof that is between 1 and 5 millimeters,e.g., between 1 and 3 millimeters. In an embodiment, the vent tube isadapted to passively permit the passage of the fluid out of the lumen.Alternatively, the vent tube is adapted to be coupled to a suctionsource, whereby to actively facilitate the passage of the fluid out ofthe lumen. For example, the vent tube may be adapted to be coupled tothe suction source such that during operation of the apparatus, apressure distal to the piston head is between −5 millibar and +15millibar.

In an embodiment, the piston head is adapted to be inflated so as toattain and maintain the direct contact with the wall of the colon.

For some applications:

(i) the apparatus includes an auxiliary piston head, coupled to thecarrier at a position proximal to the distal piston head,

(ii) the auxiliary piston head is adapted to be inflated so as to attainand maintain direct contact with the wall of the colon, and

(iii):

-   -   (a) at at least one time while the carrier is within the body        lumen, the distal piston head is adapted to be in a state of        being already deflated at least in part simultaneously with the        auxiliary piston head being already inflated and being advanced        distally through the colon in response to pressure from the        fluid pressure source, and    -   (b) at at least one other time while the carrier is within the        body lumen, the auxiliary piston head is adapted to be in a        state of being already deflated at least in part simultaneously        with the distal piston head being already inflated and being        advanced distally through the colon in response to pressure from        the fluid pressure source.

In an embodiment, the piston head is adapted to be intermittentlydeflated at least in part, while in the colon, whereby to facilitate thepassage of the fluid out of the lumen from the site within the lumendistal to the piston head.

In an embodiment, the apparatus includes a piston-head-pressure sensor,adapted to sense a pressure within the piston head. Alternatively oradditionally, the apparatus includes a distal pressure sensor, adaptedto sense a pressure within the colon distal to the piston head. Furtheralternatively or additionally, the apparatus includes a proximalpressure sensor, adapted to sense a pressure within the colon proximalto the piston head. For some applications, one, two, or three of thesesensors are provided.

In an embodiment, the apparatus includes:

a pressure sensor, adapted to measure a first pressure associated withoperation of the apparatus; and

a control unit, adapted to regulate a second pressure associated withoperation of the apparatus responsive to the measurement of the pressuresensor.

For example, the pressure sensor may be adapted to measure a pressureselected from the list consisting of: a pressure distal to the pistonhead, a pressure proximal to the piston head, and a pressure within thepiston head.

In an embodiment, the control unit is adapted to regulate the pressurebeing measured by the pressure sensor. Alternatively, the control unitis adapted to regulate a pressure other than that being measured by thepressure sensor.

In an embodiment, the piston head is shaped to define a proximal lobeand a distal lobe, the lobes being in fluid communication with eachother.

For some applications:

(a) a volume of a first one of the lobes is adapted to decrease inresponse to a constriction of the colon adjacent thereto,

(b) a volume of a second one of the lobes is adapted to remain constantin the absence of a change in colon diameter adjacent thereto, even ifthe volume of the first lobe is decreased, and/or

(c) a pressure within the first and second lobes is equal in steadystate, regardless of the decrease in volume of the first lobe.

In an embodiment, the piston head is adapted to be at an inflationpressure between 10 and 60 millibar during advancement through the colon(e.g., 20-50 millibar, or 30-45 millibar). Alternatively oradditionally, the piston head is adapted to advance through the colon inresponse to a pressure from the fluid pressure source that is between30% and 100% of the inflation pressure. For example, the piston head maybe adapted to advance through the colon in response to a pressure fromthe fluid pressure source that is between 50% and 100% of the inflationpressure (e.g., between 50% and 80% of the inflation pressure).

In an embodiment, the piston head is shaped to define adistally-narrowing portion, and is adapted to be inserted into the colonsuch that a tip of the distally-narrowing portion points in a distaldirection when the piston head is in the colon. For some applications, aproximal base of the distally-narrowing portion has a characteristicfully-inflated diameter that is larger than a diameter of at least apart of the colon through which the distally-narrowing portion isadapted to pass, whereby the base of the distally-narrowing portion doesnot inflate fully when the base is in that part of the colon.

There is further provided, in accordance with an embodiment of thepresent invention, a method, including:

placing a distal piston head in direct contact with a wall of a bodylumen;

applying fluid pressure to the distal piston head to advance the pistonhead distally through the body lumen; and

facilitating passage of fluid out of the lumen from a site within thelumen distal to the piston head.

In an embodiment, the method includes applying a low friction coating toan outer surface of the piston head intended for contact with the wallof the lumen, the low friction coating being suitable for facilitatingsliding of the piston head against the wall of the lumen.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andplacing the piston head includes placing the piston head in directcontact with a wall of the GI tract. In an embodiment, the GI tractincludes a colon, and placing the piston head includes placing thepiston head in direct contact with a wall of the colon.

In an embodiment, facilitating the passage of the fluid includesfacilitating the passage of the fluid out of the lumen through a venttube extending from the site distal to the piston head to a site outsideof the lumen. For some applications, facilitating the passage of thefluid includes passively permitting the passage of the fluid through thevent tube and out of the lumen. Alternatively, facilitating the passageof the fluid includes actively removing the fluid from the lumen. Forexample, actively removing the fluid may include applying to the sitedistal to the piston head a pressure between −5 millibar and +15millibar.

In an embodiment, placing the piston head in direct contact with thewall includes inflating the piston head to an extent sufficient toattain and maintain the direct contact with the wall of the colon.

In an embodiment, the method includes:

placing an auxiliary piston head proximal to the distal piston head;

inflating the auxiliary piston head to an extent sufficient to attainand maintain direct contact with the wall of the colon;

at at least one time while the distal piston head is within the bodylumen, deflating the distal piston head at least in part, such that at apost-distal-piston-head-deflation time when the distal piston head is ina state of being already deflated at least in part, the auxiliary pistonhead is inflated and advancing distally through the colon in response tothe applied fluid pressure; and

at at least one other time while the distal piston head is within thebody lumen, deflating the auxiliary piston head at least in part, suchthat at a post-auxiliary-piston-head-deflation time when the auxiliarypiston head is in a state of being already deflated at least in part,the distal piston head is inflated and advancing distally through thecolon in response to the applied pressure.

In an embodiment, facilitating the passage of the fluid out of the lumenincludes intermittently deflating the piston head at least in part.

In an embodiment, the method includes sensing a pressure within thepiston head, within the colon distal to the piston head, and/or withinthe colon proximal to the piston head.

In an embodiment, the method includes:

sensing a first pressure associated with performing the method; and

regulating a second pressure associated with performing the method,responsive to sensing the first pressure.

For example, sensing the first pressure may include sensing a pressureselected from the list consisting of: a pressure distal to the pistonhead, a pressure proximal to the piston head, and a pressure within thepiston head.

For some applications, regulating the second pressure includesregulating the first pressure. Alternatively, regulating the secondpressure does not include regulating the first pressure.

In an embodiment, inflating the piston head includes inflating thepiston head at an inflation pressure between 10 and 60 millibar.Alternatively or additionally, applying the fluid pressure includessetting the fluid pressure to between 30% and 100% of the inflationpressure (e.g., between 50% and 100% of the inflation pressure, orbetween 50% and 80% of the inflation pressure).

In an embodiment, inflating the piston head includes inflating thepiston head at an inflation pressure between 20 and 50 millibar (e.g.,between 30 and 45 millibar).

There is therefore provided, in accordance with an embodiment of thepresent invention, apparatus for use with abiologically-compatible-fluid pressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

a distal piston head coupled to a distal portion of the carrier andadapted to:

-   -   be in direct contact with a wall of the lumen after the carrier        has been inserted into the lumen,    -   be advanced distally through the body lumen in response to        pressure from the fluid pressure source, and    -   facilitate passage of fluid out of the lumen from a site within        the lumen distal to the piston head; and

an optical system having distal and proximal ends, and including:

-   -   an image sensor, positioned at the proximal end of the optical        system;    -   an optical member having distal and proximal ends, and shaped so        as to define a lateral surface, at least a distal portion of        which is curved, configured to provide omnidirectional lateral        viewing; and    -   a convex mirror, coupled to the distal end of the optical        member, wherein the optical member and the mirror have        respective rotational shapes about a common rotation axis.

For some applications, the convex mirror is shaped so as define anopening through which distal light can pass.

There is also provided, in accordance with an embodiment of the presentinvention, apparatus for use with a biologically-compatible-fluidpressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

an inflatable distal piston head coupled to a distal portion of thecarrier, the distal piston head shaped so as to define a proximal lobeand a distal lobe in fluid communication with each other, the distalpiston head adapted to:

-   -   be inflated so as to attain direct contact with a wall of the        lumen after the carrier has been inserted into the lumen, and    -   be advanced distally through the body lumen in response to        pressure from the fluid pressure source; and

a flexible vent tube, passing through the proximal and distal lobes ofthe piston head, and opening to a site within the lumen distal to thepiston head, and adapted to facilitate passage of fluid from the site.

There is further provided, in accordance with an embodiment of thepresent invention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

a balloon coupled to a distal portion of the carrier and adapted to bein direct contact with a wall of the lumen after the carrier has beeninserted into the lumen; and

a hydrophilic substance disposed at an external surface of the balloon.

There is still further provided, in accordance with an embodiment of thepresent invention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a balloon coupled to a distal portion of the carrier and adapted to bein direct contact with a wall of the lumen after the carrier has beeninserted into the lumen, the balloon having a characteristic thicknessof no more than 20 microns.

For some applications, the balloon has a characteristic thickness of nomore than 10 microns.

There is additionally provided, in accordance with an embodiment of thepresent invention, apparatus for use with abiologically-compatible-fluid pressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a distal piston head coupled to a distal portion of the carrier andadapted to:

-   -   be in direct contact with a wall of the lumen after the carrier        has been inserted into the lumen, and    -   be withdrawn proximally through the body lumen in response to        pressure from the fluid pressure source.

For some applications, the carrier is adapted to facilitate passage offluid out of the lumen from a site within the lumen proximal to thepiston head.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, apparatus for use with an elongate carrier forinsertion through a proximal opening of a body lumen, the apparatusincluding:

an annular balloon, shaped so as to form an opening therethrough forinsertion of the carrier, the balloon expandable to form a seal betweenthe balloon and a wall of the body lumen in a vicinity of the proximalopening;

first and second fluid pressure sources;

a first tube, coupled between the first pressure source and an interiorof the balloon; and

a second tube, coupled between the second pressure source and aninterior of the lumen distal to the annular balloon.

For some applications, at least one of the first and second pressuresources is adapted to be positioned outside the body lumen.

There is also provided, in accordance with an embodiment of the presentinvention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

an inflatable cuff, shaped so as to define an opening therethroughthrough which the carrier can be inserted, the cuff adapted to form aseal with a wall of the body lumen when the cuff is in an inflated statein a vicinity of the proximal opening.

There is further provided, in accordance with an embodiment of thepresent invention, apparatus for use with a fluid source, the apparatusincluding:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

an image-capturing device, fixed to the carrier in a vicinity of adistal end of the carrier; and

at least one fluid supply tube coupled to the carrier, the tube coupledto the fluid source,

wherein the distal end of the carrier is shaped so as to define one ormore openings in fluid communication with the tube, the openingsoriented so as to spray at least a portion of the image-capturing devicewhen fluid is provided by the fluid source.

There is still further provided, in accordance with an embodiment of thepresent invention, apparatus for use in a body lumen having a proximalopening and a wall, the apparatus including:

an elongate carrier, adapted to be inserted through the proximal openingof the body lumen;

an image-capturing device, fixed in a first vicinity of a distal end ofthe carrier, and adapted to provide omnidirectional lateral viewing; and

an inflation element, fixed in a second vicinity of the distal end, andadapted to increase a diameter of the carrier in the second vicinity toan extent sufficient to position the image-capturing device a distancefrom the wall sufficient to enable omnidirectional focusing of theimage-capturing device.

There is additionally provided, in accordance with an embodiment of thepresent invention, apparatus for use in a body lumen having a proximalopening, the apparatus including:

first and second fluid pressure sources;

an elongate carrier, adapted to be inserted through the proximal openingof the body lumen;

a distal inflatable piston head coupled to a distal portion of thecarrier, and adapted to be in direct contact with a wall of the lumenafter the carrier has been inserted into the lumen;

a first passageway in fluid communication with the first pressure sourceand a proximal portion of the lumen proximal to the piston head;

a second passageway in fluid communication with the second pressuresource and the piston head;

first and second pressure sensors, adapted to measure pressure in theproximal portion of the lumen, and in the piston head, respectively; and

a control unit, adapted to cause the piston head to be advanced distallyin the lumen by:

-   -   while the first pressure source applies a pressure to the        proximal portion of the lumen,    -   driving the second pressure source to regulate a pressure in the        piston head to be equal to the pressure in the proximal portion        of the lumen plus a positive value.

For some applications, the apparatus includes a third passageway influid communication with a portion of the lumen distal to the pistonhead and a site outside the lumen.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, apparatus for use with abiologically-compatible-fluid pressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

a piston head coupled to a distal portion of the carrier and adapted to:

-   -   form a pressure seal with a wall of the lumen after the carrier        has been inserted into the lumen, and    -   be advanced distally through the body lumen in response to        pressure from the fluid pressure source,    -   the apparatus being configured to facilitate distal advancement        of the piston head by facilitating passage of fluid out of the        lumen from a site within the lumen distal to the piston head;        and

an optical system, coupled to the carrier in a vicinity of the distalportion, the optical system having distal and proximal ends, andincluding:

-   -   an image sensor, positioned at the proximal end of the optical        system;    -   an optical member having distal and proximal ends, and shaped so        as to define a lateral surface, at least a distal portion of        which is curved, configured to provide omnidirectional lateral        viewing; and    -   a convex mirror, coupled to the distal end of the optical        member, wherein the optical member and the mirror have        respective rotational shapes about a common rotation axis.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract. In an embodiment, the GI tract includes a colon, and thecarrier is adapted to be inserted through the proximal opening of thecolon.

In an embodiment, the piston head is adapted to be in direct contactwith the wall of the GI tract after the carrier has been inserted intothe GI tract.

For some applications, the convex mirror is shaped so as to define anopening through which distal light can pass. For some applications, theoptical member is shaped so as to define a distal indentation in thedistal end of the optical member. For some applications, the opticalmember is shaped so as to define a proximal indentation in the proximalend of the optical member. For some applications, the optical systemincludes a distal lens, positioned distal to the mirror, the distal lenshaving a rotational shape about the common rotation axis. For someapplications, the optical system is configured to provide differentlevels of magnification for distal light arriving at the image sensorthrough the distal end of the optical system, and lateral light arrivingat the image sensor through the curved distal portion of the lateralsurface of the optical member.

For some applications, an outer surface of the piston head forming thepressure seal with the wall of the GI tract includes a low frictioncoating suitable for facilitating sliding of the piston head against thewall of the GI tract.

For some applications, the apparatus includes a fluid source, and atleast one fluid supply tube coupled to the carrier, the tube in fluidcommunication with the fluid source, and the distal portion of thecarrier is shaped so as to define one or more openings in fluidcommunication with the tube, the openings oriented so as to spray atleast a portion of the optical member when fluid is provided by thefluid source.

For some applications, the apparatus includes an inflation element,fixed in a vicinity of the distal portion of the carrier, and adapted toincrease a diameter of the carrier in the vicinity to an extentsufficient to position the optical member a distance from the wallsufficient to enable omnidirectional focusing of the optical system.

In an embodiment, the apparatus includes a vent tube, and the apparatusis adapted to facilitate the passage of the fluid out of the GI tractthrough the vent tube. For some applications, the vent tube is adaptedto passively permit the passage of the fluid out of the GI tract.Alternatively, the vent tube is adapted to be coupled to a suctionsource, whereby to actively facilitate the passage of the fluid out ofthe GI tract.

In an embodiment, the piston head is adapted to be inflated so as toform and maintain the pressure seal with the wall of the GI tract. Forsome applications, the piston head is adapted to be intermittentlydeflated at least in part, while in the GI tract, whereby to facilitatethe passage of the fluid out of the GI tract from the site within the GItract distal to the piston head. For some applications, the piston headis shaped to define a proximal lobe and a distal lobe, the lobes beingin fluid communication with each other.

For some applications, the apparatus includes a piston-head-pressuresensor, adapted to sense a pressure within the piston head. For someapplications, the piston-head-pressure sensor is adapted to be disposedwithin the piston head. Alternatively, the piston-head-pressure sensoris adapted to be disposed in a vicinity of the proximal opening of theGI tract. For some applications, the piston-head-pressure sensor isadapted to be disposed outside of the GI tract.

There is also provided, in accordance with an embodiment of the presentinvention, apparatus for use with a biologically-compatible-fluidpressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

an inflatable piston head coupled to a distal portion of the carrier,the piston head shaped so as to define a proximal lobe and a distal lobein fluid communication with each other, the piston head adapted to:

-   -   be inflated so as to form a pressure seal with a wall of the        lumen after the carrier has been inserted into the lumen, and    -   be advanced distally through the body lumen in response to        pressure from the fluid pressure source.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract. In an embodiment, the GI tract includes a colon, and thecarrier is adapted to be inserted through the proximal opening of thecolon.

In an embodiment, the piston head is adapted to be in direct contactwith the wall of the GI tract after the carrier has been inserted intothe GI tract.

For some applications, a volume of a first one of the lobes is adaptedto decrease in response to a constriction of the GI tract adjacentthereto, a volume of a second one of the lobes is adapted to remainconstant in the absence of a change in GI tract diameter adjacentthereto, even if the volume of the first lobe is decreased, and apressure within the first and second lobes is equal in steady state,regardless of the decrease in volume of the first lobe.

For some applications, the distal lobe has a diameter substantiallyequal to a diameter of the GI tract. For some applications, the distallobe has a length of between 3 and 5 cm. For some applications, thepiston head is shaped so as to define at least one lobe in addition tothe first and second lobes.

For some applications, the piston head is shaped so as to define anintermediate portion at which the proximal and distal lobes articulate.For some applications, the intermediate portion has a diameter equal tobetween 10% and 40% of a diameter of the distal lobe.

In an embodiment, the apparatus includes a flexible vent tube, passingthrough the proximal and distal lobes of the piston head, and opening toa site within the GI tract distal to the piston head, and adapted tofacilitate distal advancement of the piston head by facilitating passageof fluid from the site. For some applications, the apparatus includes asuction source, adapted to actively facilitate the passage of the fluidfrom the site.

For some applications, a volume of a first one of the lobes is adaptedto decrease in response to a constriction of the GI tract adjacentthereto, a volume of a second one of the lobes is adapted to remainconstant in the absence of a change in GI tract diameter adjacentthereto, even if the volume of the first lobe is decreased, and apressure within the first and second lobes is equal in steady state,regardless of the decrease in volume of the first lobe.

For some applications, the distal lobe has a diameter substantiallyequal to a diameter of the GI tract. For some applications, the distallobe has a length of between 3 and 5 cm. For some applications, thepiston head is shaped so as to define at least one lobe in addition tothe first and second lobes.

For some applications, the piston head is shaped so as to define anintermediate portion at which the proximal and distal lobes articulate.For some applications, the intermediate portion has a diameter equal tobetween 10% and 40% of a diameter of the distal lobe.

There is further provided, in accordance with an embodiment of thepresent invention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

a balloon coupled to a distal portion of the carrier and adapted to bein direct contact with a wall of the lumen after the carrier has beeninserted into the lumen; and

a hydrophilic substance disposed at an external surface of the balloon.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract. In an embodiment, the GI tract includes a colon, and thecarrier is adapted to be inserted through the proximal opening of thecolon.

For some applications, the balloon is shaped so as to define a proximallobe and a distal lobe, the lobes being in fluid communication with eachother.

There is still further provided, in accordance with an embodiment of thepresent invention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a balloon coupled to a distal portion of the carrier and adapted to bein direct contact with a wall of the lumen after the carrier has beeninserted into the lumen, an outer surface of the balloon in contact withthe wall of the lumen including a low friction coating suitable forfacilitating sliding of the balloon against the wall of the lumen.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract. In an embodiment, the GI tract includes a colon, and thecarrier is adapted to be inserted through the proximal opening of thecolon.

For some applications, the low friction coating includes a lubricant.

For some applications, the balloon is shaped so as to define a proximallobe and a distal lobe, the lobes being in fluid communication with eachother.

There is additionally provided, in accordance with an embodiment of thepresent invention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a balloon coupled to a distal portion of the carrier and adapted to bein direct contact with a wall of the lumen after the carrier has beeninserted into the lumen, the balloon having a characteristic thicknessof no more than 20 microns.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract. In an embodiment, the GI tract includes a colon, and thecarrier is adapted to be inserted through the proximal opening of thecolon.

For some applications, the balloon has a characteristic thickness of nomore than 10 microns. For some applications, an outer surface of theballoon in contact with the wall of the GI tract includes a low frictioncoating suitable for facilitating sliding of the balloon against thewall of the GI tract. For some applications, an outer surface of theballoon in contact with the wall of the GI tract includes a hydrophilicsubstance suitable for facilitating sliding of the balloon against thewall of the GI tract.

For some applications, the balloon is shaped so as to define a proximallobe and a distal lobe, the lobes being in fluid communication with eachother.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, apparatus for use with abiologically-compatible-fluid pressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a piston head coupled to a distal portion of the carrier and adapted to:

-   -   form a pressure seal with a wall of the lumen after the carrier        has been inserted into the lumen, and    -   be withdrawn proximally through the body lumen in response to        pressure from the fluid pressure source.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe piston head is adapted to form the pressure seal with the wall ofthe GI tract after the carrier has been inserted into the GI tract In anembodiment, the GI tract includes a colon, and the piston head isadapted to form the pressure seal with the wall of the colon after thecarrier has been inserted into the colon.

In an embodiment, the piston head is adapted to be in direct contactwith the wall of the GI tract after the carrier has been inserted intothe GI tract.

For some applications, an outer surface of the piston head forming thepressure seal with the wall of the GI tract includes a low frictioncoating suitable for facilitating sliding of the piston head against thewall of the GI tract.

For some applications, the piston head is shaped so as to define aproximal lobe and a distal lobe, the lobes being in fluid communicationwith each other.

For some applications, the apparatus includes a pressure-applicationtube in fluid communication with (a) a distal site within the GI tractdistal to the piston head, and (b) the fluid pressure source, the tubeadapted to introduce the pressure to the distal site.

For some applications, the apparatus includes:

a fluid source;

an image-capturing device, coupled to the carrier in a vicinity of adistal end of the carrier; and

at least one fluid supply tube coupled to the carrier, the tube in fluidcommunication with the fluid source,

and the distal end of the carrier is shaped so as to define one or moreopenings in fluid communication with the tube, the openings oriented soas to spray at least a portion of the image-capturing device when fluidis provided by the fluid source.

In an embodiment, the apparatus is adapted to facilitate passage offluid out of the GI tract from a proximal site within the GI tractproximal to the piston head. For some applications, the apparatusincludes a vent tube in fluid communication with the proximal site andoutside the GI tract, the tube adapted to facilitate passage of fluidfrom the proximal site to the outside, so as to reduce a pressure at theproximal site. For some applications, the vent tube is adapted topassively permit the passage of the fluid from the proximal site. Forsome applications, the apparatus includes a suction source coupled tothe vent tube, adapted to actively facilitate the passage of the fluidfrom the proximal site.

In an embodiment, the piston head is adapted to be inflated so as toform and maintain the pressure seal with the wall of the GI tract. Forsome applications, the apparatus includes a piston-head-pressure sensor,adapted to sense a pressure within the piston head. For someapplications, the piston-head-pressure sensor is adapted to be disposedwithin the piston head. For some applications, the piston-head-pressuresensor is adapted to be disposed in a vicinity of the proximal openingof the GI tract. For some applications, the piston-head-pressure sensoris adapted to be disposed outside of the GI tract.

For some applications, the apparatus includes a distal pressure sensor,adapted to sense a pressure within the GI tract distal to the pistonhead. For some applications, the distal pressure sensor is adapted to bedisposed distal to the piston head. For some applications, the distalpressure sensor is adapted to be disposed in a vicinity of the proximalopening of the GI tract. For some applications, the distal pressuresensor is adapted to be disposed outside of the GI tract.

For some applications, the apparatus includes a proximal pressuresensor, adapted to sense a pressure within the GI tract proximal to thepiston head. For some applications, the proximal pressure sensor isadapted to be disposed in a vicinity of the piston head. For someapplications, the proximal pressure sensor is adapted to be disposed ina vicinity of the proximal opening of the GI tract. For someapplications, the proximal pressure sensor is adapted to be disposedoutside of the GI tract.

For some applications, the apparatus includes a pressure sensor, adaptedto measure a first pressure associated with operation of the apparatus;and a control unit, adapted to regulate a second pressure associatedwith operation of the apparatus responsive to the measurement of thepressure sensor. For some applications, the pressure sensor is adaptedto measure a pressure selected from the list consisting of: a pressuredistal to the piston head, a pressure proximal to the piston head, and apressure within the piston head.

There is also provided, in accordance with an embodiment of the presentinvention, apparatus including:

an elongate carrier adapted to be inserted through a proximal opening ofa body lumen;

an annular balloon, shaped so as to form an opening therethrough forinsertion of the carrier, the balloon adapted to be at least partiallyinserted into the proximal opening, and to be expandable to form apressure seal between the balloon and a wall of the body lumen in avicinity of the proximal opening;

first and second fluid pressure sources;

a first tube, coupled between the first pressure source and an interiorof the balloon; and

a second tube, coupled between the second pressure source and aninterior of the lumen distal to the annular balloon.

In an embodiment, the body lumen includes a colon, the proximal openingincludes a rectum, and the balloon is adapted to be at least partiallyinserted into the rectum, and to be expandable to form the pressure sealbetween the balloon and the wall of the colon.

For some applications, at least one of the first and second pressuresources is adapted to be positioned outside the colon.

For some applications, the apparatus includes a ring coupled to theballoon, the ring adapted to abut against the rectum, and the ringshaped so as to form an opening therethrough for insertion of thecarrier.

For some applications, the first pressure source includes a poweredfluid pressure source. Alternatively, the first pressure source includesa manually-operated fluid pressure source. For some applications, themanually-operated pressure source includes a syringe.

There is further provided, in accordance with an embodiment of thepresent invention, apparatus including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

an inflatable cuff, shaped so as to define an opening therethroughthrough which the carrier can be inserted, the cuff adapted to form apressure seal with a wall of the body lumen when the cuff is in aninflated state in a vicinity of the proximal opening.

In an embodiment, the body lumen includes a colon, the proximal openingincludes a rectum, and the carrier is adapted to be inserted through therectum of the colon.

There is still further provided, in accordance with an embodiment of thepresent invention, apparatus for use with a fluid source, the apparatusincluding:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen;

an image-capturing device, fixed to the carrier in a vicinity of adistal end of the carrier; and

at least one fluid supply tube coupled to the carrier, the tube in fluidcommunication with the fluid source,

wherein the distal end of the carrier is shaped so as to define one ormore openings in fluid communication with the tube, the openingsoriented so as to spray at least a portion of the image-capturing devicewhen fluid is provided by the fluid source.

In an embodiment, the body lumen includes a colon, and the carrier isadapted to be inserted through the proximal opening of the colon.

For some applications, the distal end of the carrier is shaped so as todefine between 4 and 10 openings through which the fluid flows whenprovided by the fluid source. For some applications, the openings aredisposed circumferentially about the distal end of the carrier. For someapplications, the openings are positioned at a circumferential angle, soas to create a vortex around the image-capturing device when the fluidis provided by the fluid source.

For some applications, the image-capturing device includes an opticalmember that is shaped so as to define a lateral surface configured toprovide omnidirectional lateral viewing, and the openings are orientedso as to spray at least a portion of the lateral surface of the opticalmember. For some applications, the optical member is shaped so as todefine a forward surface configured to provide forward viewing, and theopenings are oriented so as to spray at least a portion of the forwardsurface of the optical member.

There is additionally provided, in accordance with an embodiment of thepresent invention, apparatus for use in a body lumen having a proximalopening, the apparatus including:

an elongate carrier, adapted to be inserted through the proximal openingof the lumen;

an image-capturing device, fixed in a first vicinity of a distal end ofthe carrier, and adapted to provide omnidirectional lateral viewing; and

an inflation element, fixed in a second vicinity of the distal end, andadapted to increase a diameter of the carrier in the second vicinity toan extent sufficient to position the image-capturing device a distancefrom a wall of the lumen sufficient to enable omnidirectional focusingof the image-capturing device.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract.

For some applications, the inflation element is adapted to increase thediameter of the carrier in the second vicinity such that theimage-capturing device is at least 15 mm from the wall.

For some applications, the inflation element includes an expandablesponge. Alternatively or additionally, the inflation element includes aset of one or more rings, selected from the list consisting of:inflatable rings, and expandable rings. Further alternatively oradditionally, the inflation element includes an inflatable balloon.

In an embodiment, the GI tract includes a colon, and the carrier isadapted to be inserted through the proximal opening of the colon. Forsome applications, the inflation element is adapted to increase thediameter of the carrier in the second vicinity to between 30 and 45 mm.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, apparatus for use in a body lumen having aproximal opening, the apparatus including:

first and second fluid pressure sources;

an elongate carrier, adapted to be inserted through the proximal openingof the body lumen;

an inflatable piston head coupled to a distal portion of the carrier,and adapted to form a pressure seal with a wall of the lumen after thecarrier has been inserted into the lumen;

a first passageway in fluid communication with the first pressure sourceand a proximal portion of the lumen proximal to the piston head;

a second passageway in fluid communication with the second pressuresource and the piston head;

first and second pressure sensors, adapted to measure a first measurablepressure in the proximal portion of the lumen, and a second measurablepressure in the piston head, respectively; and

a control unit, adapted to cause the piston head to be advanced distallyin the lumen by:

-   -   while the first pressure source applies a first applied pressure        to the proximal portion of the lumen,    -   regulating the second measurable pressure in the piston head to        be equal to the first measurable pressure in the proximal        portion of the lumen plus a positive value, by driving the        second pressure source to apply a second applied pressure.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe carrier is adapted to be inserted through the proximal opening ofthe GI tract. In an embodiment, the GI tract includes a colon, and thecarrier is adapted to be inserted through the proximal opening of thecolon.

an embodiment, the piston is adapted to be in direct contact with thewall of the GI tract after the carrier has been inserted into the GItract.

For some applications, the apparatus includes a third passageway influid communication with a portion of the GI tract distal to the pistonhead and a site outside the GI tract.

For some applications, the first passageway has a diameter of between 3and 6 mm.

For some applications, the first pressure sensor is adapted to bedisposed in a vicinity of the piston head. Alternatively, for someapplications, the first pressure sensor is adapted to be disposed in avicinity of the proximal opening of the GI tract. For some applications,the first pressure sensor is adapted to be disposed outside of the GItract.

For some applications, the second pressure sensor is adapted to bedisposed within the piston head. For some applications, the secondpressure sensor is adapted to be disposed in a vicinity of the proximalopening of the GI tract. For some applications, the second pressuresensor is adapted to be disposed outside of the GI tract.

For some applications, the positive value is between 1 and 5 millibar.For some applications, the positive value is between 1.5 and 2.5millibar.

For some applications, the control unit is adapted to set the secondmeasurable pressure in the piston head at an initial value prior toapplication of the first applied pressure, by driving the secondpressure source to apply the second applied pressure. For someapplications, the initial value is between 5 and 15 millibar, and thecontrol unit is adapted to set the second measurable pressure at between5 and 15 millibar. For some applications, the control unit is adapted toregulate the second measurable pressure to be equal to the greater of:(a) the initial value, and (b) the first measurable pressure plus thepositive value.

There is also provided, in accordance with an embodiment of the presentinvention, apparatus for use with a biologically-compatible-fluidpressure source, including:

an elongate carrier, adapted to be inserted through a proximal openingof a body lumen; and

a distal piston head coupled to a distal portion of the carrier andadapted to:

-   -   form a pressure seal with a wall of the lumen after the carrier        has been inserted into the lumen, and    -   be advanced distally through the body lumen in response to        pressure from the fluid pressure source applied to an external        surface of the distal piston head.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe distal piston head is adapted to form the pressure seal with thewall of the GI tract after the carrier has been inserted into the GItract. In an embodiment, the GI tract includes a colon, and the distalpiston head is adapted to form the pressure seal with the wall of thecolon after the carrier has been inserted into the colon.

In an embodiment, the distal piston head is adapted to be in directcontact with the wall of the GI tract after the carrier has beeninserted into the GI tract.

For some applications, an outer surface of the distal piston headforming the pressure seal with the wall of the GI tract includes a lowfriction coating suitable for facilitating sliding of the distal pistonhead against the wall of the GI tract.

For some applications, the apparatus includes:

a fluid source;

an optical member coupled in a vicinity of the distal portion of thecarrier; and

at least one fluid supply tube coupled to the carrier, the tube in fluidcommunication with the fluid source,

and the distal portion of the carrier is shaped so as to define one ormore openings in fluid communication with the tube, the openingsoriented so as to spray at least a portion of the optical member whenfluid is provided by the fluid source.

For some applications, the apparatus includes:

an optical system including an optical member configured to provideomnidirectional lateral viewing; and

an inflation element, fixed in a vicinity of the distal portion of thecarrier, and adapted to increase a diameter of the carrier in thevicinity to an extent sufficient to position the optical member adistance from the wall sufficient to enable omnidirectional focusing ofthe optical system.

In an embodiment, the apparatus is adapted to facilitate distaladvancement of the distal piston head by facilitating passage of fluidout of the GI tract from a distal site within the GI tract distal to thedistal piston head. For some applications, the apparatus is adapted tofacilitate the passage of an amount of the fluid out of the GI tractfrom the distal site sufficient to maintain a pressure of less than 10millibar at the distal site. For some applications, the apparatus isadapted to facilitate the passage of at least 100 cc of the fluid out ofthe GI tract from the distal site, per minute that the distal pistonhead advances distally. For some applications, the apparatus is adaptedto facilitate the passage of at least 300 cc of the fluid out of the GItract from the distal site, per minute that the distal piston headadvances distally.

For some applications, the apparatus is adapted to facilitate thepassage of at least 3 cc of the fluid out of the GI tract from thedistal site, percentimeter that the distal piston head advancesdistally. For some applications, the apparatus is adapted to facilitatethe passage of at least 10 cc of the fluid out of the GI tract from thedistal site, per centimeter that the distal piston head advancesdistally.

For some applications, the apparatus includes a vent tube, and theapparatus is adapted to facilitate the passage of the fluid out of theGI tract from the distal site within the GI tract through the vent tube.For some applications, the vent tube is shaped to define an innerdiameter thereof that is between 1 and 3 millimeters. For someapplications, the vent tube is adapted to passively permit the passageof the fluid out of the GI tract from the distal site within the GItract.

For some applications, the vent tube is adapted to be coupled to asuction source, whereby to actively facilitate the passage of the fluidout of the GI tract from the distal site within the GI tract. For someapplications, the vent tube is adapted to be coupled to the suctionsource such that during operation of the apparatus, a pressure distal tothe distal piston head is between −5 millibar and +15 millibar.

For some applications, the apparatus includes a suction source coupledto the vent tube, adapted to actively facilitate the passage of thefluid out of the GI tract from the distal site within the GI tract. Forsome applications, the suction source is adapted to maintain a pressuredistal to the distal piston head is between −5 millibar and +15millibar.

For some applications, the distal piston head is adapted to be inflatedso as to form and maintain the pressure seal with the wall of the GItract, and the distal piston head is adapted to be intermittentlydeflated at least in part, while in the GI tract, whereby to facilitatethe passage of the fluid out of the GI tract from the site within the GItract distal to the distal piston head.

In an embodiment, the distal piston head is adapted to be inflated so asto form and maintain the pressure seal with the wall of the GI tract.For some applications, the apparatus includes an auxiliary piston head,coupled to the carrier at a position proximal to the distal piston head;the auxiliary piston head is adapted to be inflated so as to form andmaintain an auxiliary pressure seal with the wall of the GI tract; and(a) at at least one time while the carrier is within the GI tract, thedistal piston head is adapted to be in a state of being already deflatedat least in part, simultaneously with the auxiliary piston head beingalready inflated and being advanced distally through the GI tract inresponse to pressure from the fluid pressure source, and (b) at at leastone other time while the carrier is within the GI tract, the auxiliarypiston head is adapted to be in a state of being already deflated atleast in part, simultaneously with the distal piston head being alreadyinflated and being advanced distally through the GI tract in response topressure from the fluid pressure source.

For some applications, the apparatus includes a piston-head-pressuresensor, adapted to sense a pressure within the distal piston head. Forsome applications, the piston-head-pressure sensor is adapted to bedisposed within the distal piston head. For some applications, thepiston-head-pressure sensor is adapted to be disposed in a vicinity ofthe proximal opening of the GI tract. For some applications, thepiston-head-pressure sensor is adapted to be disposed outside of the GItract. For some applications, the apparatus includes a distal pressuresensor, adapted to sense a pressure within the GI tract distal to thedistal piston head. For some applications, the distal pressure sensor isadapted to be disposed distal to the distal piston head. Alternatively,for some applications, the distal pressure sensor is adapted to bedisposed in a vicinity of the proximal opening of the GI tract. For someapplications, the distal pressure sensor is adapted to be disposedoutside of the GI tract.

For some applications, the apparatus includes a proximal pressuresensor, adapted to sense a first measurable pressure, within a proximalportion of the GI tract proximal to the distal piston head. For someapplications, the apparatus includes a distal pressure sensor, adaptedto sense a pressure distal to the distal piston head. For someapplications, the proximal pressure sensor is adapted to be disposed ina vicinity of the distal piston head.

For some applications, the proximal pressure sensor is adapted to bedisposed in a vicinity of the proximal opening of the GI tract. For someapplications, the proximal pressure sensor is adapted to be disposedoutside of the GI tract. For some applications, the apparatus includes apiston-head-pressure sensor, adapted to sense a second measurablepressure, within the distal piston head. For some applications, thepressure source includes a first pressure source, adapted to apply afirst applied pressure to the proximal portion of the GI tract, and theapparatus includes:

a second pressure source, adapted to apply a second applied pressure toan interior of the distal piston head; and

a control unit, adapted to advance the distal piston head distally inthe GI tract by:

-   -   while the first pressure source applies the first applied        pressure to the proximal portion,    -   regulating the second measurable pressure in the distal piston        head to be equal to the first measurable pressure in the        proximal portion of the GI tract plus a positive value, by        driving the second pressure source to apply the second applied        pressure.

For some applications, the apparatus includes a pressure sensor, adaptedto measure a first pressure associated with operation of the apparatus;and a control unit, adapted to regulate a second pressure associatedwith operation of the apparatus responsive to the measurement of thepressure sensor. For some applications, the pressure sensor is adaptedto measure a pressure selected from the list consisting of: a pressuredistal to the distal piston head, a pressure proximal to the distalpiston head, and a pressure within the distal piston head. For someapplications, the control unit is adapted to regulate the pressure beingmeasured by the pressure sensor. For some applications, the control unitis adapted to regulate a pressure other than that being measured by thepressure sensor.

For some applications, the distal piston head is shaped to define aproximal lobe and a distal lobe, the lobes being in fluid communicationwith each other.

For some applications, a volume of a first one of the lobes is adaptedto decrease in response to a constriction of the GI tract adjacentthereto, a volume of a second one of the lobes is adapted to remainconstant in the absence of a change in GI tract diameter adjacentthereto, even if the volume of the first lobe is decreased, and apressure within the first and second lobes is equal in steady state,regardless of the decrease in volume of the first lobe.

For some applications, the distal piston head is adapted to be at aninflation pressure between 10 and 60 millibar during advancement throughthe GI tract. For some applications, the distal piston head is adaptedto advance through the GI tract in response to a pressure from the fluidpressure source that is between 30% and 100% of the inflation pressure.For some applications, the distal piston head is adapted to advancethrough the GI tract in response to a pressure from the fluid pressuresource that is between 50% and 100% of the inflation pressure.

For some applications, the distal piston head is adapted to be at aninflation pressure between 20 and 50 millibar during advancement throughthe GI tract. For some applications, the distal piston head is adaptedto be at an inflation pressure between 30 and 45 millibar duringadvancement through the GI tract. For some applications, the distalpiston head is adapted to advance through the GI tract in response to apressure from the fluid pressure source that is between 30% and 100% ofthe inflation pressure. For some applications, the distal piston head isadapted to advance through the GI tract in response to a pressure fromthe fluid pressure source that is between 50% and 100% of the inflationpressure. For some applications, the distal piston head is adapted toadvance through the GI tract in response to a pressure from the fluidpressure source that is between 50% and 80% of the inflation pressure.

For some applications, the distal piston head is shaped to define adistally-narrowing portion, and is adapted to be inserted into the GItract such that a tip of the distally-narrowing portion points in adistal direction when the distal piston head is in the GI tract. Forsome applications, a proximal base of the distally-narrowing portion hasa characteristic fully-inflated diameter that is larger than a diameterof at least a part of the GI tract through which the distally-narrowingportion is adapted to pass, whereby the base of the distally-narrowingportion does not inflate fully when the base is in that part of the GItract.

There is further provided, in accordance with an embodiment of thepresent invention, apparatus for use in a body lumen having a proximalopening, the apparatus including:

an elongate carrier, adapted to be inserted through the proximal openingof the body lumen;

an inflatable piston head coupled to a distal portion of the carrier,and adapted to form a pressure seal with a wall of the lumen after thecarrier has been inserted into the lumen; and

a biologically-compatible fluid proximal pressure source, adapted to bein fluid communication with a proximal portion of the lumen proximal tothe piston head, and to apply pressure sufficient to advance the carrierdistally through the body lumen.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe piston head is adapted to form the pressure seal with the wall ofthe GI tract. In an embodiment, the GI tract includes a colon, and thepiston head is adapted to form the pressure seal with the wall of thecolon.

In an embodiment, the piston head is adapted to be in direct contactwith the wall of the GI tract.

For some applications, the apparatus includes a first passageway, andthe proximal pressure source is in the fluid communication with theproximal portion of the GI tract via the first passageway.

For some applications, the apparatus includes a piston pressure source,adapted to be in fluid communication with the piston head, and to applypressure to the piston head in order to inflate the piston head.

For some applications, the apparatus includes a second passageway, andthe piston pressure source is in the fluid communication with the pistonhead via the second passageway.

For some applications, the apparatus includes a proximal pressuresensor, adapted to measure a pressure in the proximal portion of the GItract; and a piston pressure sensor, adapted to measure a pressure inthe piston head.

For some applications, the apparatus includes a proximal pressuresensor, adapted to measure a pressure in the proximal portion of the GItract For some applications, the proximal pressure sensor is adapted tobe disposed in a vicinity of the piston head. Alternatively, for someapplications, the proximal pressure sensor is adapted to be disposed ina vicinity of the proximal opening of the GI tract. For someapplications, the proximal pressure sensor is adapted to be disposedoutside of the GI tract.

For some applications, the apparatus includes a piston pressure sensor,adapted to measure a pressure in the piston head. For some applications,the piston pressure sensor is adapted to be disposed within the pistonhead. For some applications, the piston pressure sensor is adapted to bedisposed in a vicinity of the proximal opening of the GI tract. For someapplications, the piston pressure sensor is adapted to be disposedoutside of the GI tract.

For some applications, the apparatus includes a vent tube, adapted to bein fluid communication with a distal portion of the GI tract distal tothe piston head, and with outside of the GI tract, and to facilitatedistal advancement of the piston head by facilitating passage of fluidout of the GI tract from the distal portion. For some applications, theapparatus includes a distal pressure sensor, adapted to measure apressure in the distal portion of the GI tract. For some applications,the distal pressure sensor is adapted to be disposed distal to thepiston head. For some applications, the distal pressure sensor isadapted to be disposed in a vicinity of the proximal opening of the GItract. For some applications, the distal pressure sensor is adapted tobe disposed outside of the GI tract.

For some applications, the apparatus is adapted to facilitate thepassage of an amount of the fluid out of the GI tract from the distalportion sufficient to maintain a pressure of less than 10 millibar atthe distal portion.

For some applications, the vent tube is adapted to passively permit thepassage of the fluid out of the GI tract from the distal portion.

For some applications, the apparatus includes a suction source coupledto the vent tube, adapted to actively facilitate the passage of thefluid out of the GI tract from the distal portion.

For some applications, the apparatus is adapted to facilitate thepassage of at least 100 cc of the fluid out of the GI tract from thedistal portion, per minute that the piston head advances distally. Forsome applications, the apparatus is adapted to facilitate the passage ofat least 300 cc of the fluid out of the GI tract from the distalportion, per minute that the piston head advances distally.

For some applications, the apparatus is adapted to facilitate thepassage of at least 3 cc of the fluid out of the GI tract from thedistal portion, percentimeter that the piston head advances distally.For some applications, the apparatus is adapted to facilitate thepassage of at least 10 cc of the fluid out of the GI tract from thedistal portion, per centimeter that the piston head advances distally.

There is still further provided, in accordance with an embodiment of thepresent invention, apparatus for use in a body lumen having a proximalopening, the apparatus including:

an elongate carrier, adapted to be inserted through the proximal openingof the body lumen;

an inflatable piston head coupled to a distal portion of the carrier,and adapted to form a pressure seal with a wall of the lumen after thecarrier has been inserted into the lumen;

a biologically-compatible fluid proximal pressure source, adapted to bein fluid communication with a proximal portion of the lumen proximal tothe piston head, and to apply pressure sufficient to advance the carrierdistally through the body lumen; and

a piston head pressure sensor, adapted to sense a piston head pressurein the piston head, the piston head pressure sensor disposed in avicinity of the proximal opening of the lumen, and in fluidcommunication with an interior of the piston head.

In an embodiment, the lumen includes a gastrointestinal (GI) tract, andthe piston head is adapted to form the pressure seal with the wall ofthe GI tract. In an embodiment, the GI tract includes a colon, and thepiston head is adapted to form the pressure seal with the wall of thecolon.

In an embodiment, the piston head is adapted to be in direct contactwith the wall of the GI tract.

For some applications, the piston head pressure sensor is adapted to bein fluid communication with the interior of the piston head via apassageway, a proximal end of which is disposed in the vicinity of theproximal opening of the GI tract.

For some applications, the piston head pressure sensor is adapted to bedisposed outside of the GI tract.

For some applications, the apparatus includes a biologically-compatiblefluid piston head pressure source, adapted to be in fluid communicationwith the interior of the piston head via a passageway, and the pistonhead pressure sensor is adapted to be in fluid communication with theinterior of the piston head via the passageway.

For some applications, the apparatus includes a proximal portionpressure sensor, adapted to sense a proximal portion pressure in theproximal portion of the GI tract, and disposed in a vicinity of theproximal opening of the GI tract. For some applications, the proximalportion pressure sensor is adapted to be disposed outside of the GItract.

For some applications, the apparatus includes a distal portion pressuresensor, adapted to sense a distal portion pressure in a distal portionof the GI tract distal to the piston head, and disposed in a vicinity ofthe proximal opening of the GI tract. For some applications, the distalportion pressure sensor is adapted to be disposed outside of the GItract.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method including:

forming a pressure seal between a piston head and a wall of a bodylumen;

advancing the piston head distally through the body lumen by:

-   -   applying fluid pressure to an external surface of the piston        head, and    -   facilitating passage of fluid out of the lumen from a site        within the lumen distal to the piston head; and

providing omnidirectional lateral viewing from a vicinity of the pistonhead.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, a method including:

forming a pressure seal between a wall of a body lumen and a piston headshaped so as to define a proximal lobe and a distal lobe in fluidcommunication with each other; and

advancing the piston head distally through the body lumen by applyingfluid pressure to an external surface of the piston head.

There is also provided, in accordance with an embodiment of the presentinvention, a method including:

providing an elongate carrier having a balloon coupled to a distalportion thereof, the balloon having a hydrophilic substance disposed atan external surface thereof; and

inserting the elongate carrier through a proximal opening of a bodylumen, such that the balloon comes in direct contact with a wall of thelumen.

There is further provided, in accordance with an embodiment of thepresent invention, a method including:

providing an elongate carrier having a balloon coupled to a distalportion thereof, an outer surface of the balloon having a low frictioncoating suitable for facilitating sliding of the balloon against thewall of the lumen; and

inserting the elongate carrier through a proximal opening of a bodylumen, such that the outer surface of the balloon comes in directcontact with a wall of the lumen.

There is still further provided, in accordance with an embodiment of thepresent invention, a method including:

providing an elongate carrier having a balloon coupled to a distalportion thereof, the balloon having a characteristic thickness of nomore than 20 microns; and

inserting the elongate carrier through a proximal opening of a bodylumen, such that the balloon comes in direct contact with a wall of thelumen.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method including:

forming a pressure seal between a piston head and a wall of a bodylumen; and

applying fluid pressure to an external surface of the piston head towithdraw the piston head proximally through the body lumen.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, a method including:

inserting an annular balloon at least partially into a proximal openingof a body lumen;

expanding the balloon to form a seal between the balloon and a wall ofthe body lumen in a vicinity of the proximal opening;

inserting an elongate carrier into the lumen through an opening thatpasses through the balloon; and

applying pressure to an interior of the lumen distal to the balloon.

There is also provided, in accordance with an embodiment of the presentinvention, a method including:

inserting an inflatable cuff at least partially into a proximal openingof a body lumen;

inflating the cuff to form a seal with a wall of the body lumen in avicinity of the proximal opening; and

inserting an elongate carrier into the lumen through an opening thatpasses through the cuff.

There is further provided, in accordance with an embodiment of thepresent invention, a method including:

inserting, through a proximal opening of a body lumen, an elongatecarrier having an image-capturing device fixed thereto in a vicinity ofa distal end thereof; and

spraying, from one or more openings in the distal end of the carrier,fluid onto at least a portion of the image-capturing device.

There is still further provided, in accordance with an embodiment of thepresent invention, a method including:

inserting, through a proximal opening of a body lumen, an elongatecarrier having an image-capturing device fixed thereto in a firstvicinity of a distal end of the carrier, for providing omnidirectionallateral viewing; and

increasing a diameter of the carrier in a second vicinity of the distalend to an extent sufficient to position the image-capturing device adistance from a wall of the lumen sufficient to enable omnidirectionalfocusing of the image-capturing device.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method including:

forming a pressure seal between an inflatable piston head and a wall ofa body lumen;

measuring a first measurable pressure in a proximal portion of the lumenproximal to the piston head, and a second measurable pressure in thepiston head; and

advancing the piston head distally through the lumen by:

-   -   applying a first applied pressure to the proximal portion of the        lumen, and    -   regulating the second measurable pressure in the piston head to        be equal to the first measurable pressure in the proximal        portion of the lumen plus a positive value, by applying a second        applied pressure to piston head.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, a method including:

forming a pressure seal between a distal piston head and a wall of abody lumen; and

applying fluid pressure to an external surface of the distal piston headto advance the piston head distally through the lumen.

There is also provided, in accordance with an embodiment of the presentinvention, a method including:

forming a pressure seal between a piston head and a wall of a bodylumen;

applying fluid pressure to an external surface of the distal piston headto advance the piston head distally through the lumen; and

sensing, at a vicinity of a proximal opening of the lumen, a piston headpressure in the piston head.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a simplified pictorial illustration of a system, constructedand operative in accordance with an embodiment of the present invention,which may be suitable for imaging body lumens, such as the GI tract;

FIGS. 2 and 3 are simplified sectional illustrations of distal andproximal portions, respectively, of the system of FIG. 1;

FIG. 4 is a simplified sectional illustration of a carrier of the systemof FIG. 1, the section being taken transverse to a longitudinal axis ofthe carrier, in accordance with an embodiment of the present invention;

FIGS. 5A, 5B and 5C are simplified pictorial illustrations of the systemof FIG. 1, showing three steps of a mode of operation thereof, whereininflatable piston heads are inflated and deflated to negotiate obstaclesin a body lumen, in accordance with an embodiment of the presentinvention;

FIG. 6 is a pictorial illustration of a system for use in a body lumen,constructed and operative in accordance with an embodiment of thepresent invention;

FIG. 7 is a pictorial illustration of an inflated conical balloon, whichis adapted for use in accordance with an embodiment of the presentinvention;

FIG. 8 is a pictorial illustration of a partially-inflated conicalballoon in a body lumen, in accordance with an embodiment of the presentinvention;

FIG. 9A is a pictorial illustration of the cross-section of a fullyinflated portion of a conical balloon, in accordance with an embodimentof the present invention;

FIG. 9B is a pictorial illustration of the cross-section of a partiallyinflated portion of a conical balloon, in accordance with an embodimentof the present invention;

FIGS. 10A and 10B are pictorial illustrations of a system for use in abody lumen, constructed and operative in accordance with an embodimentof the present invention;

FIGS. 11A and 11B are pictorial illustrations of the multi-lobed pistonhead of FIGS. 10A and 10B, in accordance with an embodiment of thepresent invention;

FIG. 12 is a schematic cross-sectional illustration of an opticalsystem, in accordance with an embodiment of the present invention;

FIGS. 13A and 13B are pictorial illustrations of another system for usein a body lumen, in accordance with an embodiment of the presentinvention;

FIG. 14 is a schematic illustration of an inserter, in accordance withan embodiment of the present invention; and

FIG. 15 is a schematic illustration of a cleaning system, in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIGS. 1-3, which illustrate a system 10,constructed and operative in accordance with an embodiment of thepresent invention.

As seen best in FIG. 3, system 10 may include a guide member 12, whichmay be constructed of any medically safe material, such as but notlimited to, plastic or metal. Guide member 12 may be formed with a firstpassageway 14 connected to a source 16 of a pressurizedbiologically-compatible fluid (“fluid pressure source 16”), such as butnot limited to, a source of pressurized air, CO₂ or water. Guide member12 may be at least partially insertable into a proximal opening 18(e.g., the rectum) of a body lumen 20 (e.g., the colon). Guide member 12may include an annular ring 22 for abutting against the proximal opening18.

Guide member 12 may be formed with a bore 24 through which an elongatecarrier 26 may be arranged for sliding movement. An O-ring 28 may beprovided for dynamically sealing carrier 26 in its sliding motionrelative to the guide member 12. Carrier 26 may be any slender wire,catheter or tube and the like, constructed of any medically safematerial, such as but not limited to, a flexible plastic or metal.Carrier 26, including its tip, may be safely deflected and steeredthrough body lumen 20.

In an embodiment of the present invention, guide member 12 comprises amicrocuff, which forms a seal with the wall of lumen 20, in order tomaintain positive pressure within lumen 20. For example, the microcuffmay comprise a cuff manufactured by Microcuff GmbH (Weinheim, Germany),and/or described in the above-mentioned PCT Publication WO 04/069057, USPatent Application Publication 2003/0000526, and/or PCT Publication WO03/045487. The creation of such positive pressure is describedhereinbelow.

A piston head 30 may be mounted on carrier 26. Piston head 30 may beinflatable, and as such may be constructed of any medically safeelastomeric material, such as but not limited to, a bladder or membranemade of polyurethane or silicone rubber, for example. An image-capturingdevice 32 may be mounted on carrier 26 distal to piston head 30. Pistonhead 30 is typically fixed to carrier 26 and sealed thereto with O-rings33, but optionally may be arranged to slide on carrier 26 up to somedistal stop which arrests further distal motion of piston head 30(image-capturing device 32 may serve as the distal stop, for example).Image-capturing device 32 may comprise, without limitation, a camera(e.g., CCD or CMOS), or alternatively x-ray, ultrasonic, MRI, infraredand/or microwave imaging devices.

Other therapeutic or diagnostic devices may be mounted on or in carrier26, such as but not limited to, a magnet, drug delivery devices (e.g.,via iontophoresis), gene therapy devices and others.

Carrier 26 may include a second passageway 34 in fluid communicationwith piston head 30, connected to a source of fluid pressure 36 (e.g.,pressurized air or water) for inflating piston head 30. For someapplications, piston head-inflation fluid pressure source 36 isregulated to maintain a generally constant pressure within piston head30, regardless of changes of volume of the piston head which occur inresponse to diameter changes of lumen 20.

A vent tube 38 may pass through or around piston head 30, having anopening 40 distal to piston head 30 through which fluid is ventable tothe outside. That is, the proximal end of vent tube 38 vents the fluidpast guide member 12 to the outside. For some applications, the proximalend of vent tube 38 may be connected to a suction source (not shown) forsucking fluid through vent tube 38. “Fluid,” as used herein, includingin the claims, includes liquids and gases.

In an embodiment, vent tube 38 is not used, but instead piston head 30is temporarily deflated (at least in part), intermittently and/or inresponse to excess pressure accumulating distal to piston head 30. Thetemporary deflation of the piston head allows venting of the distalpressure to occur through passageway 14, typically in conjunction with atemporary decoupling of passageway 14 from fluid pressure source 16.

A power supply tube 42 (e.g., containing electrical wires, fiber optics,etc.) may pass through carrier 26, for connection to image-capturingdevice 32. Alternatively, the electrical and optical components ofimage-capturing device 32 may have their own internal power source, withno need for external wiring. Image-capturing device 32 may wirelesslytransmit or receive data to or from an external processor (not shown).The components of system 10 may be fully automated with sensors andoperate in a closed or open control loop.

A fluid supply tube 44 may pass through carrier 26, which may beconnected to a fluid source (not shown), e.g., pressurized water, forcleaning the area near image-capturing device 32, or in combination withthe vent tube 38, for cleaning body lumen 20 itself (e.g., the colon).

Experiments carried out by the inventors have shown that the system, asdescribed hereinabove, is able to safely and efficiently advance acolonoscope or other tool through the colon of an anesthetized 90 kgpig. In these experiments, elongate carrier 26 was generallyradio-opaque, and its motion was tracked in real-time using fluoroscopicimaging. Vent tube 38 was utilized, having an inner diameter of 2 mm. Itacted passively (without being connected to a suction source), in orderto allow pressure accumulating distal to piston head 30 to be vented tothe outside.

In these experiments, a range of operating pressures were examined. Theproximal pressure and the pressure within the piston head (intra-headpressure) were controlled, and values were recorded at whichsatisfactory movement of piston head 30 was observed. In general, forintra-head pressures ranging between 25 and 40 millibar, movement ofpiston head 30 was observed when the proximal pressure reached 30-100%of the intra-head pressure.

Typically, when the proximal pressure was below a threshold value, nomovement was observed. As the proximal pressure was elevated above thethreshold value, piston head 30 advanced through the colon. If theproximal pressure increased significantly above the threshold pressure(e.g., 2-10 millibar above the threshold pressure), then there waspressure leakage between piston head 30 and the wall of lumen 20, andadvancement of piston head 30 ceased. In response to such a leak, theproximal pressure was lowered, vent tube 38 allowed the excessaccumulated distal pressure to vent to the outside, and movement ofpiston head 30 recommenced.

In an experiment, an inflatable piston head was formed of thin silicone,and was shaped to have a distal lobe, a proximal lobe, and anintermediate portion connecting the distal and proximal lobes. (SeeFIGS. 10A and 10B.) For an intra-head pressure of 30 millibar, thepiston head advanced through the colon when the proximal pressure wasmaintained between 10 and 20 millibar. During advancement of the pistonhead, vent tube 38 vented to the outside the pressure that accumulateddue to the advancement of the piston head. Leakage around the pistonhead was observed for proximal pressures greater than about 20 millibar.For an intra-head pressure of 40 millibar, the piston head advancedthrough the colon when the proximal pressure was maintained between 27and 30 millibar, both on straight and curved portions of the colon. Forstraight portions of the colon, proximal pressures of as low as 20millibar were also sufficient to produce satisfactory movement of thepiston head.

Although the rate of advance of the two-lobed piston head was found tovary with the selected pressures, in one experiment using a thin-walledtwo-lobed piston head, a total time of 2 minutes passed during theadvancing of a colonoscope 1.5 meters into the colon of the pig. Inanother experiment, using a thick-walled two-lobed piston head, anintra-head pressure of 70 millibar and proximal pressure of 50 millibarresulted in 1.5 meters of colonoscope advancement in 1 minute 41seconds. Thin-walled piston heads useful for these embodiments of theinvention typically have a head wall thickness between 10 and 100microns, e.g., 50 microns or less than 20 microns, or a head wallthickness of less than 10 microns. Thick-walled piston heads useful forthese embodiments of the invention typically have a head wall thicknessgreater than 100 microns, e.g., 150 microns, or 250 microns.

In another experiment, the piston head was formed of polyurethane, andwas shaped like a cone, as described hereinbelow with reference to FIGS.7-9. In this experiment, satisfactory advancement of the piston head wasobtained at a proximal pressure of 35 millibar, when the intra-headpressure was also 35 millibar. The satisfactory advancement was obtainedboth on straight and curved portions of the colon.

It is noted that in these experiments, during the time when theintra-head pressure was kept constant, the volume of the piston headchanged actively in response to changes in diameter of lumen 20.

Reference is now made to FIGS. 1, 2 and 5A-C, which illustrate operationof system 10, in accordance with an embodiment of the present invention.In this embodiment, an auxiliary piston head 46 may be mounted on thecarrier proximal to distal piston head 30. Auxiliary piston head 46,which like piston head 30 may be inflatable, may be fixed axially tocarrier 26 at a fixed distance from piston head 30. Auxiliary pistonhead 46 may be sealed with respect to carrier 26 with O-rings 47.Carrier 26 may include a third passageway 48 in fluid communication withauxiliary piston head 46, connected to a source of fluid pressure 50 forinflating auxiliary piston head 46.

System 10 may be inserted in the rectum with piston heads 30 and 46initially deflated to facilitate insertion. Distal piston head 30 maythen be gently inflated until it expands to the inner wall of body lumen20. This configuration is shown in FIG. 1. Pressurized fluid (e.g., air)from fluid pressure source 16 may be introduced into the colon throughthe first passageway 14 of guide member 12. The pressurized fluidcreates greater fluid pressure acting on the proximal side of pistonhead 30 than on the distal side of piston head 30. Opening 40 of venttube 38 may assist in creating the pressure difference across pistonhead 30, either passively, or actively via applied suction. Thispressure difference propels piston head 30 together with carrier 26distally into the body lumen (in this example, the colon), as indicatedby arrow 60. Image-capturing device 32 may capture images of body lumen20 as system 10 travels therethrough.

In an embodiment of the present invention, the techniques describedherein for propulsion by creating a pressure difference are applied in areverse manner to actively propel piston head 30 together with carrier26 proximally, i.e., to withdraw system 10 from lumen 20. Pressurizedfluid (e.g., air) from a fluid pressure source is introduced to thedistal side of piston head 30, via a pressure-application tube passingthrough or around piston head 30. Optionally, vent tube 38 serves as thepressure-application tube during withdrawal. The pressurized fluidcreates greater fluid pressure acting on the distal side of piston head30 than on the proximal side of piston head 30, thereby proximallypropelling the piston head and the carrier. A vent tube between theproximal side of piston head 30 and outside the lumen may assist increating the pressure difference across piston head 30, eitherpassively, or actively via applied suction. Optionally, passageway 14serves as the vent tube during withdrawal.

As seen in FIG. 5A, system 10 may eventually reach an obstacle or tightturn, indicated by arrow 62. In such a case, proximal piston head 46 maybe inflated and distal piston head 30 may be deflated as shown in FIG.5B. In this configuration, the pressurized fluid creates greater fluidpressure acting on the proximal side of proximal piston head 46 than onthe distal side of proximal piston head 46. This pressure differencepropels proximal piston head 46 together with carrier 26 distally, asindicated by arrow 64. This distal movement brings distal deflatedpiston head 30 past the obstacle, as seen in FIG. 5B. System 10continues its distal movement in body lumen 20 until proximal pistonhead 46 reaches the obstacle. At this point, distal piston head 30 maybe inflated and proximal piston head 46 may be deflated once again, asshown in FIG. 5C. Once again, the pressurized fluid creates greaterfluid pressure acting on the proximal side of distal piston head 30 thanon the distal side of distal piston head 30. The pressure differencepropels system 10 distally in body lumen 20, and brings proximaldeflated piston head 46 past the obstacle. The cycle may be repeated asoften as necessary.

Reference is now made to FIG. 6, which illustrates a system 68,constructed and operative in accordance with an embodiment of thepresent invention. System 68 operates in substantially the same manneras system 10, described hereinabove with reference to FIGS. 1-4, in thatdistal piston head 30 is inflated until it is in contact with body lumen20, such that a seal between piston head 30 and lumen 20 is formed.Pressurized fluid is then introduced via first passageway 14, producinga larger pressure on the proximal face of piston head 30 than on thedistal face of piston head 30, resulting in a net force acting to movepiston head 30 distally. A sufficient net pressure force results indistal movement of piston head 30 along with elongate carrier 26 and atool 79. Tool 79 may comprise an imaging device, a biopsy device, orother apparatus to be used in body lumen 20.

Additionally, for some applications of the present invention, a suctionsource 78 is coupled to opening 40 via vent tube 38 to provide suctionon the distal face of piston head 30 and facilitate the distal movementof piston head 30. Providing suction at opening 40 may also be used insome applications to remove contents of the lumen, such as excess fluidor stool, that are impeding the movement of piston head 30. For someapplications, the suction decreases an accumulation of gas distal topiston head 30 that may be uncomfortable for the patient.

System 68 typically comprises one or more pressure sensors, for examplein order to be able to improve or optimize the performance of the systemwith respect to ease and speed of movement of system 68 through lumen20. In particular, system 68 typically comprises one or more of thefollowing pressure sensors:

-   -   a first pressure sensor 70, adapted to determine the pressure        acting on the proximal face of distal piston 30;    -   a second pressure sensor 72, adapted to determine the inflation        pressure of the distal piston head; and/or    -   a third pressure sensor 74, adapted to determine the pressure        acting on the distal face of piston head 30.

For some applications, the three pressure sensors are coupled to apressure sensor bus 76, such that the various pressure readings can besent to an electromechanical or mechanical control unit (not shown),which regulates the different pressures, either automatically or withinput from the operator of the system. For some applications, only oneof the pressure sensors is included in system 68 (e.g., sensor 70,sensor 72, or sensor 74). For other applications, two of the pressuresensors are included, and one is omitted (e.g., sensor 70, sensor 72, orsensor 74).

For some applications, first pressure sensor 70 is located proximal todistal piston head 30 in a vicinity of the piston head. Alternatively,first pressure sensor 70 is located in a vicinity of fluid pressuresource 16, typically outside the body of the patient. In this latterconfiguration: (a) first pressure sensor 70 is integrated with pressuresource 16, or is positioned separately from pressure source 16; and (b)first pressure sensor 70 is in fluid communication with a proximalportion of lumen 20 proximal to piston head 30, either via firstpassageway 14, or via a separate passageway in fluid communication withfirst pressure sensor 70 and the proximal portion of lumen 20 (separatepassageway not shown). A distal end of such separate passageway isadapted to be positioned in the proximal portion of lumen 20, either ina vicinity of guide member 12, or more distally in lumen 20, such as ina vicinity of piston head 30 proximal to the piston head.

For some applications, second pressure sensor 72 is located insidedistal piston head 30. Alternatively, second pressure sensor 72 islocated in a vicinity of fluid pressure source 36, typically outside thebody of the patient. In this latter configuration, second pressuresensor 72 is in fluid communication with piston head 30, either viasecond passageway 34, or via a separate passageway in fluidcommunication with second pressure sensor 72 and piston head 30(separate passageway not shown).

For some applications, third pressure sensor 74 is located distal todistal piston head 30. Alternatively, third pressure sensor 74 islocated in a vicinity of a proximal opening of vent tube 38 (which, forapplications in which suction source 78 is provided, is in a vicinity ofthe suction source), typically outside the body of the patient. In thislatter configuration: (a) third pressure sensor 74 is integrated withsuction source 78, or is positioned separately from suction source 78;and (b) third pressure sensor 74 is in fluid communication with a distalportion of lumen 20 distal to piston head 30, either via vent tube 38,or via a separate passageway in fluid communication with third pressuresensor 72 and the distal portion of lumen 20 (separate passageway notshown).

For some applications in which third pressure sensor 78 is in fluidcommunication with the distal portion of lumen 20 via vent tube 38, asource such as suction source 78 is adapted to periodically, such asonce every 5 to 15 seconds, e.g., once every 10 seconds, generate aburst of fluid (i.e., liquid or gas) in vent tube 38, in order to clearfrom the tube any bodily material which may have entered the tubethrough opening 40. Similarly, for some applications in which thirdpressure sensor 78 is in fluid communication with the distal portion oflumen 20 via a separate passageway, an additional source of pressurecoupled to a proximal end of the separate passageway periodicallygenerates a burst of fluid in the separate passageway.

In some embodiments of the present invention, satisfactory performanceof system 68 is attained by maintaining a pressure on the proximal sideof piston head 30 at about 25 millibar gauge, a pressure on the distalside of piston head 30 at about 5 millibar gauge, and a pressure insidepiston head 30 at about 20 millibar gauge. These values typically range,as appropriate, between about +10 and +50 millibar, −5 and +15 millibar,and +10 and +60 millibar, respectively.

For some applications, during distal advancement of system 68, thepressure inside piston head 30 is maintained within about 5 millibar ofthe pressure differential across either side of piston head 30. Forexample, using the exemplary numbers cited above, a pressureddifferential across the piston head is 25 millibar−5 millibar=20millibar. By maintaining the pressure inside piston head 30 within 5millibar of the pressure differential, the pressure inside piston head30 would generally remain between 15 and 25 millibar. The pressurewithin piston head 30 is typically maintained near this differentialpressure when piston head 30 comprises a flexible but substantiallynon-elastic material (e.g., a material such as a polyurethane thatstretches less than 10% during inflation at less than 50 millibar). Forembodiments in which piston head 30 comprises a flexible and elasticmaterial (e.g., a material comprising silicone that stretches more than10% during inflation at less than 50 millibar), the pressure withinpiston head 30 is typically greater than the differential pressure.

In an embodiment of the present invention, during distal advancement ofsystem 68, the pressure inside piston head 30 is set to an initialvalue, such as between about 5 and 15 millibar, e.g., about 10 millibar.The pressure on the proximal side of piston head 30 is increased,typically gradually, and, simultaneously, the pressure inside pistonhead 30 is regulated to be the greater of (a) its initial value and (b)the pressure on the proximal side of piston head 30 plus a value such asa constant value. Typically, this constant value is between about 1 andabout 5 millibar, e.g., between about 1.5 and about 2 millibar, such asabout 2 millibar. Once system 68 begins advancing distally, the pressureon proximal head 30 generally declines or remains level, despite thecontinuous application of pressure by pressure source 16. A diameter offirst passageway 14 is typically of a value sufficiently small to limitthe increase over time of the pressure proximal to piston head 30 whensystem 68 is advancing distally. For example, the diameter of firstpassageway may be between about 3 and about 6 mm. In general, in thisembodiment, substantially real-time control of the pressure in pistonhead 30 is exercised, while real-time control of the pressure in lumen20 proximal to the piston head is not necessarily exercised.

Other combinations of the distal, proximal, and inside pressures forpiston head 30 may be better suited for some applications, and the abovenumbers are not meant to limit the various operating pressures ofembodiments of the current invention. Additionally, for someapplications of the present invention, the various pressures acting onpiston head 30 are regulated depending on where in the lumen the pistonhead is located.

Although FIG. 6 only shows a distal piston head, it is to be understoodthat the scope of the present invention includes a system comprising aproximal piston head, as shown in FIG. 1, comprising the variouspressure control and measuring apparatus described hereinabove withregard to distal piston head 30 of FIG. 6.

Reference is now made to FIG. 7, which illustrates an inflatable pistonhead 80, constructed and operative in accordance with an embodiment ofthe present invention. Inflatable piston head 80 comprises an inflatableballoon that has the general form of a body of revolution about the axisformed by elongate carrier 26, wherein the distal end has a smallerdiameter than the proximal end. Piston head 80 typically comprises amaterial that is flexible but substantially inelastic in the range ofpressures typically encountered, such that the shape of the piston headis not substantially changed by elastic deformation when the piston headis inflated. Alternatively, piston head 80 comprises a flexible andelastic material. In some embodiments of the present invention,inflatable piston head 80 has the shape of a cone, as shown in FIG. 7.It is noted that whereas a cone is formed by rotating a straight lineabout an axis of revolution, other shapes for inflatable piston head 80are formed by rotating curved lines about an axis of revolution. Forexample, a parabola or circular arc may be used to generate appropriateshapes. In the context of the present patent application and in theclaims, all such shapes which become narrower towards their distal endare referred to as having a “distally-narrowing portion.”

For some embodiments of the present invention, the base of inflatablepiston head 80 is flat. In some other embodiments, the base ofinflatable piston head 80 is curved, wherein the curvature may be eitherconcave or convex.

FIG. 8 shows an application of inflatable piston head 80, in accordancewith an embodiment of the present invention. Piston head 80 is typicallyinserted into lumen 20 in a deflated state and subsequently inflateduntil appropriate contact is made with the lumen. Due to the shape ofinflatable piston head 80, most of a fully-inflated portion 82 of thepiston head is not in substantial contact with lumen 20, while apartially-inflated portion 84 of the piston head is in contact withlumen 20, once the piston head is fully pressurized. A good seal betweenpiston head 80 and lumen 20 is typically obtained where fully-inflatedportion 82 meets partially-inflated portion 84.

FIGS. 9A and 9B show cross-sections of the fully-inflated portion andthe partially-inflated portion, respectively, in accordance with anembodiment of the present invention. Resistance of lumen 20 to radialexpansion prevents the entire piston head from fully inflating (e.g., asshown in FIG. 7). Thus, partially-inflated portion 84 typically becomessomewhat wrinkled along the length of its contact with lumen 20.

Inflatable piston head 80 is regulated to respond to changes in thediameter of lumen 20 by inflating more as the lumen diameter increases,and by deflating as the lumen diameter decreases, all while maintainingsatisfactory contact with the lumen. Since inflatable piston head 80 istypically made of a substantially inelastic material, a relativelymodest pressure is needed to inflate the piston head. The inflationpressure is chosen to maintain an appropriate seal between the pistonhead and the lumen, without undue pressure on the lumen.

FIGS. 10A and 10B are pictorial illustrations of a multi-lobed pistonhead 100 for use in body lumen 20, constructed and operative inaccordance with an embodiment of the present invention. Except fordifferences as noted, apparatus and techniques described hereinabovewith respect to other piston heads are typically adapted for use withpiston head 100.

Piston head 100 comprises a distal lobe 102 and a proximal lobe 104.Lobes 102 and 104 articulate at an intermediate portion 106. In anembodiment, dimensions of piston head 100 include: (a) a diameter D1 ofdistal lobe 102, which is substantially equal to the diameter of lumen20, so as to make a satisfactory seal therewith, (b) a diameter D2 ofintermediate portion 106, ranging from about 10% to 40% of D1, and (c) alength D3 of distal lobe 102, ranging from about 3 to 5 cm. It is notedthat although multi-lobed piston head 100 only comprises two lobes, thescope of the present invention includes multi-lobed piston heads havingmore lobes (e.g., 3, 4, or 5 lobes).

Distal and proximal lobes 102 and 104 are in fluid communication witheach other through intermediate portion 106. In steady state, as well asat the levels of movement typically encountered during advancementthrough the colon, the pressure within lobe 102 is substantially thesame as the pressure within lobe 104. Thus, passageway 34 and fluidpressure source 36 (FIG. 2) regulate the pressure within both lobessubstantially simultaneously. The diameters of the two lobes, however,typically vary independently, in response to changes in the shape oflumen 20 adjacent to each of the lobes. Typically, as with all of theinflatable piston heads described herein, fluid is actively added to orremoved from the piston head to maintain a generally constant pressurewithin the piston head.

In an embodiment of the present invention, piston head 30 and/or carrier26 of system 10 and/or system 68 comprises a low friction coating, whichacts to reduce the friction between piston head 30 and lumen 20, therebyeasing the movement of piston head 30 and/or carrier 26 in lumen 20. Forexample, piston head 30 and/or carrier 26 may comprise a biocompatiblelow friction coating. Alternatively or additionally, piston head 30and/or carrier 26 comprises a hydrophilic coating. Additionally oralternatively, the low friction coating comprises a suitable lubricant.

FIGS. 11A and 11B are pictorial illustrations of multi-lobed piston head100, in accordance with an embodiment of the present invention. In FIGS.11A and 11B, the following tubes described hereinabove are shown:

-   -   second passageway 34 in fluid communication with both lobes 102        and 104 of piston head 100, connected to source of fluid        pressure 36;    -   vent tube 38, passing through lobes 102 and 104 of piston head        100, and having opening 40 distal to piston head 100 through        which fluid is ventable to the outside;    -   fluid supply tube 44, passing through piston head 100, for        cleaning the area near image-capturing device 32, or in        combination with vent tube 38, for cleaning body lumen 20        itself.

Second passageway 34, vent tube 38, and fluid supply tube 44 aretypically flexible, which allows for the bending of piston head 100, asshown in FIG. 11B.

FIG. 12 is a schematic cross-sectional illustration of an optical system220, in accordance with an embodiment of the present invention. For someapplications, image-capturing device 32 comprises optical system 220.Optical system 220 comprises an optical assembly 230 and an image sensor232, such as a CCD or CMOS sensor.

Optical system 220 is typically configured to enable simultaneousforward and omnidirectional lateral viewing. Light arriving from theforward end of an optical member 234, and light arriving from thelateral surface of the optical member travel through substantiallyseparate, non-overlapping optical paths. The forward light and thelateral light are typically (but not necessarily) processed to createtwo separate images, rather than a unified image. For some applications,the forward view is used primarily for navigation within a body region,while the omnidirectional lateral view is used primarily for inspectionof the body region.

Optical assembly 230 comprises, at a distal end thereof, a convex mirror240 having a rotational shape that has the same rotation axis as opticalmember 234. Optical member 234 is typically shaped so as to define adistal indentation 244 at the distal end of the optical member, i.e.,through a central portion of mirror 240. Alternatively, optical member234 is shaped without indentation 244, but instead mirror 240 includes anon-mirrored portion in the center thereof.

Typically, optical assembly 230 further comprises a distal lens 252 thathas the same rotation axis as optical member 234. For some applications,optical assembly 230 further comprises one or more proximal lenses 258,e.g., two proximal lenses 258. Proximal lenses 258 are positionedbetween optical member 234 and image sensor 232, so as to focus lightfrom the optical member onto the image sensor.

For some applications, optical system 220 is configured to enableomnidirectional lateral viewing, without enabling forward viewing.

For some applications, a hydrophobic coating is applied to one or moreof the transparent surfaces of optical assembly 220 that are in contactwith body lumen 20.

Techniques described herein may be performed in combination withtechniques described in U.S. Provisional Patent Application No.60/571,438, filed May 14, 2004, entitled, “Omnidirectional andforward-looking imaging device,” which is assigned to the assignee ofthe present application and is incorporated herein by reference.

Reference is now made to FIGS. 13A and 13B, which are pictorialillustrations of a system 310 (not to scale), in accordance with anembodiment of the present invention. System 310 is generally similar tosystem 10 and/or system 68, except as described hereinbelow.Image-capturing device 32 of system 310 typically comprises opticalsystem 220, described hereinabove with reference to FIG. 12, or anotheromnidirectional imaging device. System 310 is typically advanceddistally into lumen 20 using techniques described hereinabove withreference to systems 10 and/or 68.

System 310 is withdrawn in a proximal direction by: (a) inflating lumen20, using conventional inflation techniques for withdrawing endoscopes,and (b) pulling carrier 26 in a proximal direction. During withdrawal,the distal end of the system sometimes comes near or in contact with thewall of lumen 20, as shown in FIG. 13A. For example, lumen 20 may beinflated to a diameter D1 of between about 40 and about 70 mm, andsystem 310 may have an initial distal diameter D2 in a vicinity ofimaging-capturing device 32 of between about 8 and about 15 mm. Whensystem 310 is near the wall of lumen 20, the distance between thelateral portion of optical system 220 of image-capturing device 32 maybe less than the minimum focal length necessary for clearomnidirectional lateral viewing.

System 310 comprises an inflation element 320, which is adapted toincrease the distal diameter of system 310 from D2 (FIG. 13A) to D3(FIG. 13B). D3 is typically between about 30 and about 45 mm. Thisincreased distal diameter ensures that image-capturing device 32 is adistance from the wall of lumen 20 sufficient to enable focusing of theomnidirectional lateral image. For example, this increased distaldiameter may ensure that a central axis of image-capturing device 32 isat least a distance D4 of 15 mm from the wall of lumen 20. For someapplications, inflation element 320 comprises a sponge, which expands,for example, when exposed to liquid. Alternatively, inflation element320 comprises a set of inflatable or expandable rings. Furtheralternatively, inflation element 320 comprises an inflatable balloon,which is typically contained within the body of system 310.

Reference is now made to FIG. 14, which is a schematic illustration ofan inserter 330 for use with system 10 and/or system 68, in accordancewith an embodiment of the present invention. Inserter 330 is adapted tobe at least partially insertable into proximal opening 18 (e.g., therectum) of body lumen 20 (e.g., the colon). Inserter 330 typicallycomprises an annular ring 332 for abutting against proximal opening 18,and an annular balloon 336 that is coupled to ring 332. Ring 332 andballoon 336 are shaped so as to define a bore 334 through which carrier26 is arranged for sliding movement. Balloon 336 expands to form a sealbetween the balloon and the wall of lumen 20 in a vicinity of proximalopening 18, thereby helping maintain positive pressure created withinbody lumen 20.

Inserter 330 comprises first passageway 14 connected to fluid pressuresource 16 (as described hereinabove with reference to FIGS. 1-3, forexample), and a tube 338 for applying a positive pressure to inflateballoon 336. Tube 338 is connected to a fluid pressure source 340, whichmay comprise a powered fluid pressure source (such as is available in anoperating room) or a manually-operated fluid pressure source (such as asyringe). When fluid pressure source 340 comprises a syringe, thesyringe is typically removed after balloon 336 has been inflated, andtube 338 and/or balloon 336 is sealed to maintain the pressure, e.g.,using a check valve (valve not shown). For some applications, pressuresource 16 and pressure source 340 are derived from a common fluidpressure source.

Reference is now made to FIG. 15, which, is a schematic illustration ofa cleaning system 350 for use with system 10 and/or system 68, inaccordance with an embodiment of the present invention. Cleaning system350 is shaped to define one or more openings 360 (e.g., between about 4and about 10) coupled to fluid supply tube 44. Openings 360 are disposedcircumferentially about the distal end of carrier 26, and oriented sothat they spray at least a portion of image-capturing device 32. Forapplications in which image-capturing device 32 comprises optical system220, as described hereinabove with reference to FIG. 12, openings 360are typically oriented to spray at least a portion of the lateralomnidirectional portion of optical assembly 230, and, optionally, aportion of the distal forward portion of the assembly. For someapplications, openings 360 are positioned at a circumferential angle, soas to create a vortex around image-capturing device 32.

Although the piston head has been described in embodiments of thepresent invention as being in direct contact with the wall of the GItract, the scope of the invention includes establishing contact betweenthe piston head and the wall of the GI tract Through an intermediary,such as a sheath surrounding the piston head.

Techniques described herein may be performed in conjunction withtechniques described in the following patent applications, which areassigned to the assignee of the present application and are incorporatedherein by reference: (a) U.S. patent application Ser. No. 10/838,648 toGross et al., entitled, “Pressure-propelled system for body lumen,”filed May 3, 2004, and (b) a U.S. provisional patent application toGross et al., entitled, “Pressure-propelled system for body lumen,”filed on or about Jan. 9, 2004.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1. Apparatus for use in a body lumen having a proximal opening, theapparatus comprising: an elongate carrier, adapted to be insertedthrough the proximal opening of the lumen, an image-capturing device,fixed in a first vicinity of a distal end of the carrier, saidimage-capturing device being configured to provide omnidirectionallateral viewing; and an inflation element, fixed in a second vicinity ofthe distal end, and adapted to increase a diameter of the carrier in thesecond vicinity to an extent sufficient to position the image-capturingdevice a distance from a wall sufficient to enable omnidirectionalfocusing of the image-capturing device.
 2. The apparatus of claim 1wherein said inflation element comprises a distal piston head adaptedto: form a pressure seal with a wall of the lumen after the carrier hasbeen inserted into the lumen, and be advanced distally through the bodylumen in response to pressure from the fluid pressure source applied toan external surface of the distal piston head.
 3. The apparatusaccording to claim 2, wherein the lumen includes a gastrointestinal (GI)tract, and wherein the distal piston head is adapted to form thepressure seal with the wall of the GI tract after the carrier has beeninserted into the GI tract.
 4. The apparatus according to claim 3,wherein the GI tract includes a colon, and wherein the distal pistonhead is adapted to form the pressure seal with the wall of the colonafter the carrier has been inserted into the colon.
 5. The apparatusaccording to claim 3, wherein the distal piston head is adapted to be indirect contact with the wall of the GI tract after the carrier has beeninserted into the GI tract.
 6. The apparatus according to claim 3,wherein an outer surface of the distal piston head forming the pressureseal with the wall of the GI tract comprises a low friction coatingsuitable for facilitating sliding of the distal piston head against thewall of the GI tract.
 7. The apparatus according to claim 3, comprising:a fluid source; an optical member coupled in a vicinity of the distalportion of the carrier; and at least one fluid supply tube coupled tothe carrier, the tube in fluid communication with the fluid source,wherein the distal portion of the carrier is shaped so as to define oneor more openings in fluid communication with the tube, the openingsoriented so as to spray at least a portion of the optical member whenfluid is provided by the fluid source.
 8. The apparatus according toclaim 3, and comprising a hydrophilic substance disposed at an externalsurface of the distal piston head.
 9. The apparatus according to claim3, wherein the distal piston head is adapted to be in contact with thewall of the GI tract after the carrier has been inserted into the GItract.
 10. The apparatus according to claim 2, wherein the apparatus isadapted to facilitate distal advancement of the distal piston head byfacilitating passage of fluid out of the GI tract from a distal sitewithin the GI tract distal to the distal piston head.
 11. The apparatusaccording to claim 10, comprising a vent tube, wherein the apparatus isadapted to facilitate the passage of the fluid out of the GI tract fromthe distal site within the GI tract through the vent tube.
 12. Theapparatus according to claim 11, wherein the vent tube is adapted to becoupled to a suction source, whereby to actively facilitate the passageof the fluid out of the GI tract from the distal site within the GItract.
 13. The apparatus according to claim 11, wherein the vent tube isadapted to passively permit the passage of the fluid out of the GI tractfrom the distal site within the GI tract.
 14. The apparatus according toclaim 2, wherein the distal piston head is adapted to be inflated so asto form and maintain the pressure seal with the wall of the GI tract.15. The apparatus according to claim 14, comprising an auxiliary pistonhead, coupled to the carrier at a position proximal to the distal pistonhead, wherein the auxiliary piston head is adapted to be inflated so asto form and maintain an auxiliary pressure seal with the wall of the GItract, and wherein: (a) at least one time while the carrier is withinthe GI tract, the distal piston head is adapted to be in a state ofbeing already deflated at least in part, simultaneously with theauxiliary piston head being already inflated and being advanced distallythrough the GI tract in response to pressure from the fluid pressuresource, and (b) at least one other time while the carrier is within theGI tract, the auxiliary piston head is adapted to be in a state of beingalready deflated at least in part, simultaneously with the distal pistonhead being already inflated and being advanced distally through the GSItract in response to pressure from the fluid pressure source.
 16. Theapparatus according to claim 14, comprising a piston-head-pressuresensor, adapted to sense a pressure within the distal piston head. 17.The apparatus according to claim 14, comprising a distal pressuresensor, adapted to sense a pressure within the GI tract distal to thedistal piston head.
 18. The apparatus according to claim 14, comprisinga proximal pressure sensor, adapted to sense a first measurablepressure, within a proximal portion of the GI tract proximal to thedistal piston head.
 19. The apparatus according to claim 18, comprisinga distal pressure sensor, adapted to sense a pressure distal to thedistal piston head.
 20. The apparatus according to claim 14, comprising:a pressure sensor, adapted to measure a first pressure associated withoperation of the apparatus; and a control unit, adapted to regulate asecond pressure associated with operation of the apparatus responsive tothe measurement of the pressure sensor.
 21. The apparatus according toclaim 14, wherein the distal piston head is shaped to define a proximallobe and a distal lobe, the lobes being in fluid communication with eachother.
 22. The apparatus according to claim 21, wherein a volume of afirst one of the lobes is adapted to decrease in response to aconstriction of the GI tract adjacent thereto, wherein a volume of asecond one of the lobes is adapted to remain constant in the absence ofa change in GI tract diameter adjacent thereto, even if the volume ofthe first lobe is decreased, and wherein a pressure within the first andsecond lobes is equal in steady state, regardless of the decrease involume of the first lobe.
 23. The apparatus according to claim 2,comprising an image-capturing device coupled to the carrier.
 24. Theapparatus according to claim 2, wherein the piston head is adapted to bewithdrawn proximally through the body lumen in response to pressure fromthe fluid pressure source.
 25. The apparatus according to claim 2,wherein the fluid pressure source includes a gas pressure source, andwherein the distal piston head is adapted to be advanced distally inresponse to gas pressure from the gas pressure source.
 26. The apparatusaccording to claim 2, wherein the body lumen includes a colon and theproximal opening includes a rectum, wherein the apparatus comprises anannular balloon, shaped so as to form an opening therethrough forinsertion of the carrier, the balloon adapted to be at least partiallyinserted into the rectum, and to be expandable to form a pressure sealbetween the balloon and a wall of the colon in a vicinity of the rectum.27. The apparatus according to claim 2, comprising a tool configured tobe coupled to the distal portion of the carrier.
 28. The apparatusaccording to claim 27, wherein the tool comprises a biopsy tool.
 29. Theapparatus according to claim 1, wherein the inflation element is adaptedto increase the diameter of the carrier in the second vicinity such thatthe image-capturing device is at least 15 mm from the wall.
 30. Theapparatus according to claim 1, wherein the inflation element comprisesan expandable sponge.
 31. The apparatus according to claim 1, whereinthe inflation element comprises a set of one or more rings, selectedfrom the list consisting of: inflatable rings, and expandable rings. 32.The apparatus according to claim 1, wherein the inflation elementcomprises an inflatable balloon.
 33. The apparatus according to claim 1,wherein the inflation element is adapted to increase the diameter of thecarrier in the second vicinity to between 30 and 45 mm.